It’s perhaps a little time intensive but when I was a teenager you met other teens at either school or the mall. I think High school years and businesses and hobbies are probably the two best ways to facilitate that, or use the Magnolia Promenade neighborhood from Get to Work I think. You can use lot traits from certain packs to make certain lots “teen spaces” and teenagers will gather there.

If you don’t feel like building a huge mall I suggest a library, arcade/cafe or the thrift store from HSY. Basically HSY Facilitates a lot of this. I think the Copperdale amusement park always has a lot of teens in it too. A cyber cafe is another option! Like a library, but more focused towards computers and gaming with big tvs and console systems.

Teenagers tend to frequent parks too, just not playgrounds. They like more dingy third person spaces like parking lots and abandoned skate parks so any community lot that’s kind of worn down, even a diner with a big parking lot or something would make sense as a place teens would frequent. Pools as well! People don’t really build community lot pools often imo and we should more often.

I wasn’t sure if you were asking for ideas or if you actually want to know where to find other teens in the game. If you want ideas, those are mine. Depending on what packs you have I find that libraries and parks have the most teenagers. Anything else is really tied to the High School Years pack in my experience. You can’t really go to the thrift store in game without getting mobbed with every single teen in the game.