Yes, of course, any high ground clearance vehicle (like RAV4 EV) will likely have a handling and aerodynamic improvement with lowering (assuming the lowering is done properly).
Warranties on cars sold in the USA can't be arbitrarily voided. Any warranty repair that can be blamed on a modification, however, could be denied.
If you lowered the car by heating up the springs, and then made a warranty claim for bad springs, it will be denied. But, a warranty claim for a radio repair couldn't likely be denied because the car was lowered.