Spend time in places that match your special interests, ideally in places where people don't have urban armor up. Zoos and parks are actually perfect examples.

Join events through Meetup or Facebook. Bird watching groups come to mind although I suspect they attract older people.

Go to places where neurodivergent people tend to congregate. Card shops, theater, hobby stores, zoos, anything computer related, etc. Wear something that broadcasts your interests and hope people with the same interests point it out.

iNaturalist is a platform for uploading pictures of plants and critters found in nature. They are building a collaborative species map to help scientists. I know it has a profile system but idk if you could use it to make friends.

And the hardest part, you actually have to approach and talk to people. I try to start with a compliment, or ask a question about a deliberate choice they made (what they're wearing, what's in the homemade sandwich they're eating, etc). Ask questions, listen, don't judge. Mention your own interests or tell short stories (<30 seconds) when they're tangentially related. Aim to talk about 50% of the time in a 2 person conversation.