What are the chances of a 1200 rated player winning a chess tournament?

What are the chances of me (currently rated 1200+) winning my high school chess tournament?

The tournament is on the 11th of January 2023. It's my second tournament ever. I ended up 3rd in my 1st tournament back in 2018, but this time I'm afraid my opponents actually know how to play. 

Do you have any tips on how to prepare for this event?

Depends on a lot of things out of your control. 

You can certainly find out through observation if there are any players playing at lunch or after school.  You have time to get in a few games and see what kind of competition you are facing.

@1

"I ended up 3rd in my 1st tournament back in 2018" ++ Then your chances are good. 

"Do you have any tips on how to prepare for this event?"
++ 'Above all else, before playing in competitions a player must have regard to his health, for if he is suffering from ill-health he cannot hope for success. In this connection the best of all tonics is 15 to 20 days in the fresh air, in the country.' - Botvinnik

Could be a bunch of 1000 rated players only or the tournament is restricted to very young players with low rating, so the results in 2018 isn't exactly going to be representative of the current tournament.

Be cool, just enjoy the game. Do your best.

If you are aware of the participants inside, you could study some of their past games (if available).

Can I assume that this is a high school tournament within your school and not an inter-school tournament?