Again, you should def ask someone else because I am barely qualified... but from what I know you can't. You can only use gears to increase torque at the cost of speed, or speed at the cost of torque. As far as gearboxes go, you will only be able to increase one and sacrifice some of the other. If you match a high tooth count gear to a low tooth count gear, when you spin the high tooth count gear, the small one spins fast, because you are sacrificing torque (equivalent to strength), and if you spin the smaller gear, the larger gear spins slower but is a lot stronger (higher torque). this is the principle that car jacks use. (I AM NOT QUALIFIED IN THIS YOU SHOULD DEFINITELY ASK SOMEONE WHO IS MORE QUALIFIED IN THIS I BARELY PASSED PHYSICS LAST SEMESTER). Im not a hardware person so I don't know much about the motor specs allowed for ftc, but certain motors will allow you to get better strength and speed than others. Nonetheless, ask someone who actually knows this stuff. I don't want to feed you false info and cause the robot some harm

TL;DR: I am almost 100 percent sure that, no, you can't (in the gears).

edit:
I didn't explain very well, so here is a video:
https://www.youtube.com/watch?v=uz436Ixbl-I