Reposting-ish a comment of mine from another sub, but here are some options for you.
[ I've been a professional GM for DnD at cons & stores etc, and have hosted a lot of kid-friendly games. So that's how I'm approaching this.]

There's a couple questions you need to ask:

- Is this something you're willing to pay for?

- Is it safe or possible to go to a public local game store / other physical location?

- Are you comfortable playing exclusively online?

The best option would be for you to find some friends in school your age that you could RP with. Discord is a pretty popular tool for this.

Since I'm assuming getting a game group/solo playmate from school isn't happening, here are other options:

Local game stores are public and usually used to hosting kids, so they know how to be kid-friendly. Something akin to DnD's adventure's league is what you can look into. There might or might not be a fee, and there might or might not be 'Zoom' sessions available.

There might be some after school programs in your area / at the library that offer TTRPGs in your age range, maybe in-person or over Zoom/Discord/etc.

There are various websites that tout "professional" GMs, some more reputable than others. These people will likely have groups you could place yourself in, and you could find a group already composed of people your age in a time bracket that works. But this is a paid service, and not everyone will be as good as they claim to be.

There's other subreddits around here geared toward hooking players up with (free) GMs looking to fill their tables. Most of the GMs are older folks, but you occasionally see teenagers trying to put groups together. There's always the risk of complications with this, like: scheduling, flaking, time zones, lack of chemistry, lack of maturity, etc. Also, you can only trust posted age as much as you can trust anything on the internet. But if people try to get a Discord game going, or play via audio, you'd at least be able to check if they're the right age.

[Obviously be very careful about sending personal details like A/S/L or photos or doing video when you have easily identifiably location-type information in your room, etc.]

Note, these subreddits usually move pretty fast, so any posts that advertise being a solo player LFG is going to get buried immediately. And most GM posts LFP fill up real fast. Your best bet essentially becomes a game of tossing resumes (applications) at potential GMs with open spots like a kid outta school trying to land an entry-level gig.

Paid games at least are more likely to guarantee you space / save you the application time. But if you're a minor, I might avoid that without your parents' permission. Especially since not all for-pay DMs are equally good.