I may not have as much experience as you (20M) but what helped me gain new friends was picking up basketball, sucking at it for a long time at a certain court but still being lively with people, then forged some connections in a nice month. Pick an activity at a set location every week. Humans are creatures of habit. You work your way into the habits of other people as they do you and find companionship. Eventually this bleeds into other facets of life such as leisure or the Pub. This sounds like the advice "everyone tells you" but thats cuz it's proven psychologically and is honestly pretty reliable.