Networks → Open Graph Tags.

When someone shares one of your pages on Facebook, X, WhatsApp, LinkedIn or Slack, the app draws the preview from tags in the page's head: a title, a line of summary and a picture. With Add Open Graph and X card tags on, the plugin writes them from what WordPress already holds:

Title: the post's or page's own title, without your site name after it. On a category or tag archive, its name; on an author's page, their name; on a front page that lists your latest posts, the site name.
Summary: the post's excerpt (a product's short description), at most 200 characters. A post without an excerpt gets no summary. Nothing is taken from the body of a post, so the opening lines of members-only or paid content are never printed in the page's head. To give a post a summary, write a Share summary for it (below), or fill in its Excerpt box. On an archive, its description; on an author's page, their biographical info; on a front page that lists your posts, the tagline.
Picture: the featured image (a product's main image), with its size, type and alt text. Without one, the Default share picture if you set one, and otherwise your Site Icon. X gets the large card for a picture of at least 300 by 157 pixels, and the small one otherwise; the Site Icon is a logo and always gets the small one. An SVG is skipped, because X does not support them.
Address: the page's own address, never with UTM tags or a click id on it.
The site name, the site's language and, if you set one under Networks → Text, your X username.

A post behind a password gets its title and address only: no summary and no picture. While the plugin writes the tags, its share buttons follow the same rule, because they are printed under the password form, where anybody can read them. They share the title and address, and the Pinterest button, which cannot pin without a picture, is left off, whatever share picture, featured image or default share picture the post has. The Share Buttons block's preview in the editor follows the rule too, unless you have entered the post's password on your site in the same browser. For a visitor who has entered the password, the tags and buttons are as they are on any other post. With the tags switched off, or while an SEO plugin, your theme or Jetpack writes them, the Pinterest button on such a post pins its featured image, as it always has. Some themes, WordPress's own block themes among them, show the featured image above the password form anyway, so a picture that must stay private is better not set as a protected post's featured image. Search results, a page that is not found, feeds and previews get no tags.

There is nothing you have to fill in, and nothing is added to what a visitor downloads beyond the tags themselves: no script, no style, no request anywhere. The tags follow this switch only. The Display screen's settings and a post's Hide share buttons on this post are about the buttons, and do not affect the tags.

Choosing them for one post. Open the post and find the Share buttons box in the sidebar. Under Share preview are three fields, all empty until you fill them in:

Share title: the title the post is shared with, up to 120 characters. The post's own title is shown greyed in the box until you type.
Share summary: the line of summary, up to 300 characters, printed as you wrote it. The excerpt is shown greyed in the box, or "None: this post has no excerpt".
Share picture: a picture from your media library, shown instead of the featured image. Remove goes back to the featured image.

Under them is the card as Facebook, LinkedIn or Slack will draw it, with a line for each part saying where it came from, such as "Picture: the featured image". It changes as you type or choose a picture, before you save. It also follows the post's own title, excerpt and featured image as you edit them, in the block editor and in the classic editor, and, in the block editor, its password. Take an edit back, or undo it, and the card is as it was. A title you have just typed is shown as you typed it; the page itself may turn its straight quotes into curly ones. Leave a field empty and the post's own title, excerpt or picture is used.

The share title is also the text the buttons start a share with: on X, WhatsApp, Telegram, Reddit, Bluesky, Threads, Tumblr and Mastodon, as the subject of the email, and as the description of a pin. The share picture is what the Pinterest button pins, except on a post behind a password, which has no Pinterest button (see above).

Without a share title, the buttons start a share with the post's own title. On a post behind a password or a private post, that is the title without the "Protected:" or "Private:" WordPress puts in front of it on the page, in whatever language your site is in, as in this plugin's Open Graph title. A translation plugin or theme that changes the title is followed as on any other post. A copy of such a post that a page cache made before the plugin was updated still shares "Protected:" until it expires or the cache is cleared.

The fields are only there while this plugin writes the tags. With an SEO plugin active, the box names it instead ("Yoast SEO writes this page's share preview. Set the picture and text there."), and anything you filled in before is not used, so a post never has two answers. The same goes for a theme or Jetpack that writes the tags: once a post has been viewed with their tags in it, the box of every post of that type says so, and the buttons stop using what you filled in. This is noted for each type of post on its own, so a plugin that writes the tags on products only leaves the fields on your blog posts. When the tags are this plugin's again, the fields come back when a post of that type is next viewed, or up to an hour after that; switching your theme, or a plugin on or off, brings them back straight away. With the tags switched off, the box says nothing about a share preview; turn them on under Networks to use the fields.

Default share picture. Networks → Open Graph Tags → Default share picture. The picture a page is shared with when it has no share picture and no featured image: posts and pages without one, archives, and a front page that lists your posts. Leave it empty to keep using your Site Icon. It is also what the Pinterest button pins on a post with no picture of its own, so with a default picture set, the Pinterest button appears on every post except one behind a password (see above). An SVG is never used for sharing or pinned, because Facebook, X and Pinterest cannot show one.

When another plugin already writes them. Two sets of tags on one page contradict each other, so the plugin stays out of the way:

While Yoast SEO, Rank Math, All in One SEO, SEOPress, The SEO Framework, Slim SEO, Squirrly SEO, WPSSO Core or SmartCrawl is active, the tags are left to it, whether or not its own social setting is on. The panel names it.
On any page where your theme or another plugin (Jetpack's sharing, for example) has already written an Open Graph or X card tag in the head, nothing is added to that page.
A theme that prints its tags somewhere other than the head, after WordPress's own head output, is not seen. If you find two sets of tags on a page, turn one of them off.

New and existing sites. A new install has the tags on. A site that had the plugin before this setting existed keeps them off until you choose, and the Dashboard suggests them: Add Open Graph tags turns them on, No thanks hides the suggestion. You can change it under Networks at any time. On a multisite network each site has its own switch, and sites added later start with it on.

After a change. Saving anything a visitor sees asks your page cache to empty itself (NimbleCache, WP Rocket, LiteSpeed Cache, W3 Total Cache, WP Super Cache, WP Fastest Cache, SiteGround, Breeze, WP-Optimize and the Cloudflare plugin), once, as the save finishes, whether it was made on a screen, with a Dashboard button or by importing a file. That is the buttons as much as the head: the networks, the rail's and the bar's own lists, the style, where the buttons go and on which pages, the Open Graph tags, the X username, the default share picture and the follow buttons. So visitors get the change straight away, as you do while signed in. Delete all data on uninstall and the Dashboard's suggestion put nothing on a page, and empty nothing. The same caches are emptied once after each update of the plugin, on the first wp-admin screen you open, or where nobody opens one, when WordPress next runs its scheduled tasks, usually within the hour, so no cached page pairs the old buttons with the new stylesheet. An automatic update is caught up with this way too, and never while a visitor's page is loading. Switching the plugin off on a site empties them at once, so the buttons and share tags go from cached pages too, and switching it on again empties them once more, so pages cached while it was off get them back. Switched off for a whole network, each site keeps its cached pages until they expire, and empties them when the plugin is switched on for the network again. LiteSpeed Cache is asked for its pages only: its CSS and JS files, the object cache and Cloudflare stay as they are. A cache the plugin cannot reach, such as your host's own or a CDN, keeps its copies until they expire or you clear it. Facebook and the other apps keep their own copy of a preview for a while. To have Facebook read a page again, paste its address into Facebook's Sharing Debugger and press Scrape Again.