Pitch Wheel is an actual wheel - it is just a resistor pot (spring balanced) and is not very precise to be honest (it should have been done with extension springs on both sides... but anyway, does not matter that much). And you rotate the plastic wheel or joystick that covers the pot or stick of the joystick. In the case of surface controllers it can be a slide gesture, software brings it back to 0.
Mine has ×4 Pitch Bend polyphony (one player) for lower latency.
If you try to control more than that, it leads to a mess in the sound... may sound cool, but that "effect" can be done with a slide or elbow glide on the keys.