I understand exactly what OP means and I've been looking for something like this too. When it comes to sports I think it needs to be something with lower physi

I understand exactly what OP means and I've been looking for something like this too. When it comes to sports I think it needs to be something with lower physical bar such as table tennis, archery, shooting. Unlikely you can compete on world level but at least locally. For other things I think certain computer games might do but you will be competing with kids that play 12 hours every day so again you can only compete on small scale and in my experience online competitive games attract the most toxic people. You can try Geoguessr which I think is your best option. Then you have the more arty skills such as stand-up comedy, music production, cooking all can be competitive if you are into any of these and your age shouldn't matter much in fact it might help.