Yes, without CSS. Settings → Front page → Look offers six: Cards (the default), Tiles, List, Minimal, Spotlight and Boxed. Each is a shape rather than a palette, so it keeps your theme's type and colours and only changes where things sit and what their edges do. Pick one, save, and look at the help centre page. An article page and the contact form stay the same whichever you choose.
Still stuck? Ask the developers who wrote it. We aim to reply within one business day.
