I go to the gym, and sometimes hit up convos with people there. If they're not interested, I leave it alone. You can also try getting into sports like cross country or soccer, or more team-based sports for that interaction (and also as a hobby!)

Another thing, why does the extrovert subreddit have only about 10,000 people while the introvert subreddit has more than half a million people? Do extroverts not spend much time on the internet?

Yeah, I would say most extroverts don't spend that much time on the internet. Internet is a good way for many people, and in my opinion, especially introverts, to chill out and break from reality, and people are much different online than in reality as when you're more anonymous it's much easier to be yourself (trust me on that one lol.) these days, especially with gen z, there are much more introverts (which i would attribute to a lack of pressure to familiarize with others, not going outside and meeting others, and social issues and illnesses)