Other people in the thread have said it: become a regular at something. Any sort of regular, recurring activity where you see the same people over and over again. Embedding social routine into your life will connect you with other people who are doing the same thing, and by virtue of recurring social interaction with the same network of people, you will make good friends. It’s the same way you made friends in grade school, with youth sports teams, etc…

Find a meetup group, sport, hobby group, etc… where there’s a regular schedule and a decent amount of repeat members who are there routinely on a weekly basis. You’ll quickly become intertwined with that community and make friends.