Power is just the mathematical definition of multiplying torque and speed.
Power is determined by the engine that makes the power not by the gearing.
Having said that.... lower gears will allow the engine to run at higher RPM and generally make more power at any given speed. All this constantly changes while driving as it is all dynamic. The perception of drivability does seem to improve with lower gears and more torque. This is why diesels are so loved. Some day we will go to the next level up and have electric motors.