The proper air pressure will allow for the appropriate amount of sag. Sag is the amount the suspension compresses when supporting the rider, riding gear, and a portion of the bicycle. It is measured as a percentage, with the ideal percentage range being between 10-30% of the total available travel (less for shorter travel, more for longer travel). Setting up the suspension to achieve this will allow for maximum traction and an ideal suspension feel.
Volume adjusters, which we refer to as Bottomless Tokens or simply just "Tokens," allow you to change how easily the suspension is able to bottom out. Adding Bottomless Tokens makes it harder to bottom out. Occasional bottom-out is a good thing; it means that the suspension is being used to its potential. Excessive bottom-out can cause you to lose control.
Air pressure shouldn't need to change when adding or removing Bottomless Tokens. Always check sag to ensure the proper air pressure and check the maximum recommended amount of Tokens for your product.