Hi there
Making a flying game is complicated, not to discourage you just to let you know.
You can start by controlling the Movement mode of the player
Flying mode by default cancels Gravity, so your player would just float. You can create custom modes if you need to.
Besides that, you have to do all the work of setting up all the actual movement.
You can start by playing around with the Player Character’s physics or changing Velocity manually, depending on what you’re trying to achieve.
If you want gliding you may want some gravity affecting your character. In that case, instead of the Flying mode you may prefer to change gravity settings, or toggle between Flying and other Movement Mode.
Hope that helps getting you started somewhere with your project