There unfortunately is no system in Lemmy (atm) to do this smoothly. When I was on lemmy.world, I used their system they had set up separately and that worked well, but for most instances, the only process to do something like that is to DM an admin directly, which will of course have greatly varied results, and that’s if the admin isn’t supportive of the abusive mod in the first place.
It all depends on your home instance. The feed for All that you see will only ever show content from communities that other users on your instance subscribe to. So on a smaller instance, you’ll get less variety. On a very large instance like LW, you’ll get a lot.