Use blocks, and, optionally, "short-form" post types to more easily "IndieWebify" your WordPress site.
This plugin lets you:
IndieBlocks provides a number of blocks that can be used to add microformats to posts without having to tweak or know HTML. It also adds a number of "short-form" custom post types to more easily add a "microblog" to your site. (Both are optional, like, well, all of IndieBlocks features.)
IndieBlocks also "hooks" into the Micropub plugin, so that Micropub posts are given the correct post type, and, when applicable, "microformats" blocks.
If you're running a "block theme," it will attempt to add "microformats" to it. (If your theme already supports microformats, just leave this part disabled.)
There's also Webmention, which can be enabled for posts, notes, and likes (and any other post types of your choosing). This, in combination with the aforementioned microformats and this plugin's blocks, enables richer cross-site conversations. (If you're perfectly happy with your existing Webmention setup, here, too, you can simply leave this setting disabled.)
IndieBlocks, despite its name, runs just fine on sites that have the Classic Editor plugin installed, or don't (yet) use a "block theme." The Custom Post Types and Webmention options will just work, as will most of its smaller "modules." Microformats, however, will need to be added some other way. (It's absolutely okay to run a "classic" theme with microformats support and add microformats to posts by hand or through a different plugin.)