Looking back on the last two years and auditing what worked, I would say routine and lingering were the most important thing.
Trying new things is mentally draining and labor intensive, this is a fact of life for many. What worked for me was finding something I enjoyed (exercise classes) and doing it consistently multiple times a week at the same place for months. With repetition, it's very easy to make new friends. Complaining about one exercise one week turns into making comments about the music the next, and all of a sudden you're getting coffee with friends.
At the start it was very difficult, and I was very bad, but now I'm part of a community and have many close friends. Its a hour per day most days of the week. It's also a jumping off point for everything else social. It provides purpose and self-confidence. Which are prerequisites for everything else meaningful in life.