If you're interested in particular topics, you can join Fediverse groups. They work like this:

1. Join a group by following its account, leave by unfollowing
2. Posts from that group will start appearing in your timeline
3. Post to a group by mentioning it in a public post

The groups work via third party services, the most popular ones at the moment are https://chirp.social and https://a.gup.pe.

More info on discovering and creating groups at https://fedi.tips/how-to-use-groups-on-the-fediverse