Can tires be off ground on auto leveling system?

It's best to have all wheels on the ground or blocks for stability. Most unhitched multiple axle trailers that I've seen use scissor jacks which are a substitute brake.

Once movement of a raised RV starts it will continue until counter forces stop it at which point there may be damage.

Plus even 1/2" off of the ground means there is about a 6" drop before the suspension places the full weight on the tires.