How do you actually make friends as an adult?

I’m genuinely asking, because this feels way harder than it should be. I’m not looking to date or flirt. I just want real friendships the kind where you send each other memes, complain about work, talk about random stuff, and vent without it turning into something weird. Everyone says “put yourself out there”, but where? Work friendships stay surface-level. Online spaces either turn into dating or ghosting. And after a certain age, people already have their circles. How do you guys do it? How do you actually make friends as an adult?