Anything where you’re meeting the same people on repeat occasions. It’s pretty rare to form a friendship after only meeting people one or a couple of times. Friendships are often formed gradually. It’s easier growing up because it’s structured into so many things. You see the same people in classes, sports, clubs, etc. Friendships will form naturally in those settings. Try to find something to replicate that. It could be volunteer work, a workshop to learn something new, joining a community that shares a hobby. The key is bumping into the same people over and over

The information contained in past posts and comments on Reddit is immense. Usually, the easiest way for me to find advice is a Google search that includes “Reddit” in the search field. It almost always returns a comment with exactly the information I was looking for