An invitation to dinner is a good place to begin.
Oh so important a topic! Bravo to you . . . .
I joined a pinball club. 😂
I find that it's valuable to admit that new friends will not be the same as "old friends," people you've been hanging out with for twenty or thirty years (sometimes much longer). I find that I'm drawn to people I meet through common interests...meditation, writing, book groups in my case. It may be enough to discover new people in these settings that don't depend on a long history of affiliation. I realize as I'm writing this that I've met quite a few new people whose company I enjoy, but they're all in my general age cohort because they're all retired. The idea of younger friends is appealing but I'm willing to make do with new friends.