If there’s an activity or skill you’ve been wanting to get into, you could try taking a class in that. You’ll meet some other people at your approximate skill level, and it’s an opportunity to socialize.

I’ve personally met a lot of people through climbing gyms and dance classes, both activities where you’re often paired up with one other person. Bouldering is great for smalltalk as well, because people are often eager to discuss approaches to the problem.

Not everyone’s cup of tea, but I’ve also met some friends through work colleagues. A colleague of mine was going hiking with friends and invited me along, and since the friends didn’t work in the same company as us it felt disconnected enough from work for me at least.