In June 2023 we updated the version of WordPress and included 2 new themes: Twenty Twenty-two and Twenty Twenty-three. The Twenty Twenty-four them was added in 2024. These are themes that support Site Editing. This means these themes are a lot more customisable than standard WordPress themes.

Here is a good video on the different between block themes and the older classic themes.

Twenty Twenty-Two is the first-ever default block theme

Twenty Twenty-Three includes a collection of ten community-submitted style variations.

Full site editing’s features, include (links to wordpress.org documentation):

• Site Editor: an editor that allows you to edit all parts of your site, navigate between templates, and more.

• Styles: a feature that allows you to customize your site, including individual blocks, as much as you’d like with different colors, typography, layouts, and more.

• Templates: edit, create, and manage templates used by pages, posts, and other content.

• Template parts: a way to organize and display groups of blocks as part of a block template mainly for site structure, like Headers and Footers.

• Theme blocks including the Navigation block, Query Loop block, and more.

From Twenty Twenty-Three – WordPress.org Documentation

This very short video help understand how Block Themes work January 2024.