Bluesky has reply-gating (you can set who can reply to a post, like people you follow or a given list or no one) and is now testing out post-publication reply locking. 

I just want to yell for a second about how humane and consent-forward these features are, especially after seeing some people here losing their minds when someone asked for gating recently because they felt (alas, not a paraphrase) entitled to always be able to respond.