plank --preferences and found this slider.
What is it?
Pressure reveal is a feature designed to make it harder to accidentally un-hide the dock. Instead of revealing any time the cursor hits the bottom row of pixels on your display, it reveals when you continue to push your cursor past the bottom row of pixels on your display. In this way, it should still be easy to reveal the dock when you actually intend to do so, but harder to accidentally reveal it when you don't intend to.
At the moment, this feature is optional because it doesn't fully cooperate with input devices where you can't push the cursor past the bottom of the display: stuff like drawing tablets.