If you mean that you personally just don’t want, as a user, to see content from that instance, then no, but shortly. kbin has had the ability for users to block seeing content from particular instances for a while; lemmy has not, but I understand that it’s in the next release.
Does Threads show up as an instance I can block?
I think every instance should be able to federate with whomever they wish, I just don’t want to participate.
Yes, you can domain block threads.net just like any other mastodon/misskey/whatever server.
If you’re an instance admin, yes.
If you mean that you personally just don’t want, as a user, to see content from that instance, then no, but shortly. kbin has had the ability for users to block seeing content from particular instances for a while; lemmy has not, but I understand that it’s in the next release.