Find the communities you like. There will be communities based around wholesome memes and positivity if that’s what you want.
The other thing is to use filter lists extensively. I use Lemmy in the Boost Android app. My filter list is constantly being added to (Elon, Biden, Trump, Superbowl, Covid, etc). You’re in charge of making or finding the experience you want.
If the content is affecting you then find something else entirely. If detached from the live news cycle and watch science based YouTube channels, listen to podcasts of interest, read books and follow websites via RSS. If you don’t like it here then you don’t have to be here.