You can't force boost on in a map, that stays under player control, but you can definitely make timed sections where you'd need to get through quickly. One map that comes to mind is Outrun, in the High Impact level set (in sprint). This map has a section where the ceiling drops and crushes you if you're too slow.

The basic idea to set something like that up would be to take a killgridbox and add an animator component to it, then set up an event listener so when you touch an event trigger at the start of the section, the killgridbox starts moving toward the section, and if you're too slow, then the killgridbox animation will finish, making it cover the road you're driving on, killing you.

If you need animator and event trigger help, there's a guide here, that steps through the process:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1467701903
To accomplish this, you would only need up until the "Done" section (don't need any of the stacking stuff), and instead of using a large CubeGS, you would use a killgridbox. You would also need to make sure the animation resets when you die/reset, so you can try again.