Yeah, with no strong central control the best you can do is to persuade PDS account servers and client developers to put in good moderation filters by default, so that the average user won’t have to see that stuff assuming they land on a client/server which filter it. You can’t stop it from existing in the network, but you can coordinate ways to inhibit reach. And users who need even better tools can deploy them without having to move.
On the other hand, the work on private profiles haven’t started yet, and you can’t currently prevent yourself from getting visible to others.
On Mastodon the options are essentially just finding a server with a good moderation team and importing block list files manually, as well as keyword filters. And that’s pretty much it. The server features and moderation quality are part of the same bundle.