The best thing you can do is find a hobby. If you play a sport, even poorly, that doesn't matter as long as you enjoy it, look for a local league or club. If you play an instrument or sing, look for a local band or choir, churches can be a good place to start, even if you arent religious a lot of modern churches won't really care. If you like a craft or a hobby, find a subreddit, or a local shop or something. Fishing, boating, and other outdoor activities are also good ways to find a community

Making friends as an adult can be really difficult, especially when compared to school, but the best way to do it is a. overlapping interest and b. time spent in the same vicinity.

If you don't have a clear hobby or activity you know you like, get looking. Remember that the end goal isn't to be good at it, but to enjoy doing it.

All that said, if this doesn't sound like you at all, this is just one relatively easy way to make friends, it is not at all the only. There are plenty of other ways, I just can't really speak to them.