We just upgraded kosmos.social to Mastodon version 3.0.1 (from 2.9).

Release notes for 3.0.0, which contains all the new features: https://github.com/tootsuite/mastodon/releases/tag/v3.0.0

And there's even a video that walks you through the notes this time: https://www.youtube.com/watch?v=aYHYxOeQumo