I think I witnessed that in a past Damus bulid and can’t anymore

NIP-50 does it. But it depends on how well-indexed the relay is.

I use nostr.band to search for people. Works well.

By building giigle - nostr crawler and search engine 😉

Nostrgram.co has a view that lets you see people that are followed by people you follow or something like that so you can find more people to follow. Was really helpful to find related signal.