Rocket League comes to mind right away.

Bomberman is really fun in ranked, but a lot of people don't take it seriously because of how the game looks.

Racing games can be competitive if you try to set leaderboard scores, and Xbox has Forza which is a great series.

Does Xbox have any notable rhythm games? Genuinely not sure, but those might be an option.

Tetris / Tetris Effect could satisfy a competitive itch, if you try to set PR/high scores.

Unfortunately if you don't want to engage in anything team based, or fighting games, then your options on Xbox are a little limited. Most will come down, in some way, to competing against a leaderboard or against yourself (ie beating personal high scores, time trials, etc). That's....not necessarily a bad thing. I think that type of competition is way less toxic than other mainstream competitive games anyway.

You could also learn speed running of a game you enjoy? It's a personal journey, but it can also be highly competitive, if you want it to be. It's pretty enjoyable.