My cheat code to socialize is coming up with a joke, inventing a fun game/activity or proposing a topic i consider interesting and that may interest others.
In "nerdy" circles talking about video-games, shows, movies and comics are an easy hook. Even if you haven't watched the same media, the recommendations can give something to talk.
In content creator circles talking about writing, art, tools, creators and media is a solid conversation starter.
Also......memes XD, those can easily unify people, but don't over-rely on them.
If you wanna hang out with the people you've met using discord can be a solid option. You can create a server or join some made by friends. And if you don't have a server in common you can go through pm's.
Not sure about the specifics of twitter, so i can't advice on that tho. I see that site as a wild Pandora box where the physical manifestation of human anger lives, so i don't use it 
Hope this helps!