I went on Facebook originally as I was working remotely for an American company and we had a private group to talk about the problems with the new owner. Company folded but I still follow some American colleagues from there - put them on mute occasionally as they post incessantly about their private lives.
I am also on a couple of quite obscure artist interest groups (lovely nerdy exchange of views) a college reunion group, and a craft hobby group. I deliberately keep my number of friends right down and lock down my privacy. I joined a local group for useful info but don’t interact - there are some odd bods on there.
My insta is also very limited - I keep my followers list very small and my account is private. I follow lots of artists and photographers, so the visual base of Instagram is very important. When I first went on it I kept being shown lots of stuff that I didn’t so I just kept blocking and ignoring until the algorithm learned my preferences. I now also see some of the funnier stuff that gets repeated on from tik tok ( curtesy of originally liking some stuff my DDs send me)
So , IMO, Facebook good for community ( however you personally curate that) and Instagram good for visuals, but you need to set your own parameters for both.
Twitter I use to follow certain subjects and it’s good for getting in touch with some companies and institutions more quickly than email or phoning but, again, tailor your experience.