Which "superior" aircraft? Also I doubt if the J20s, if that unknown entity lives up to the deliberately created hype, have the legs to take off from beyond the Himalayas and reach the border areas without refuelling. Any aircraft based on the plateau will be severely degraded in fuel and payload. And India uses Israeli and French electronics. Not going to be a turkey shoot.
The Chinese have mid-air refueling. https://www.youtube.com/watch?v=vplpbShpk60