I think reddit is too big to be able to foster long term connections with other people, unless the communities you are in a small/niche enough. It might actually be easier here on lemmy/piefed/mbin because of the smaller population. I can identify users by their usernames in some of the communities I’m active in and interactions aren’t a one time thing.

Hate to say it, but Discord is pretty effective at being able to make long term connections, depending on the group of course.

Same as in-person relationships, I think the best way is to find online communities about your hobbies and interests, and look for smaller spaces, whether it be a group chat, a forum community, or even a microblogging platform.