Whether that is season tickets to a sporting event, attending church, a weekly tech meetup, volunteering on a regular schedule, a weekly open mic night, going to the same bar that has your favorite team playing, frequently attending art openings in town etc, all that matters is that people are partly there to socialize and it happens with the same group of people regularly.
Then, once you start going and seeing a few people more frequently, often you will naturally exchange phone numbers and/or get invited to another event and friendship will blossom.
And on that, seriously pay attention to your appearance. This means nice fitting clean clothing and shoes etc. Really make an effort to look good. Nothing fancy or expensive, just don't look like you just rolled out of bed. Even if you aren't in great shape, simply looking well put together helps 1000% in meeting new people.
Keep an open mind and avoid pushing your beliefs on others.
Don't give up my friend, there are so maybe people who feel just the same way that would love to hang out with you and become friends.
I've struggled with depression my entire adult life. This current one is familiar to one of my worst periods. The hardest part is the loss of interest in anything. I need to get out and see people and maintain routine which is hard when everything feels like I'm watching a black and white live stream of my life.
One foot in front of the other and hopefully I'll get myself back.
Every Sunday (or Friday or ..)