You can, its been done before. 35mm film with a sufficiently small grain size can reach resolutions over 5k, close to 6k.

A few years ago there was the 4k77 project which took probably cinematic reels of A New Hope and scanned them in at 4k. At that resolution, film grain was beginning to become visible, but given the high degradation of those specific film reels it isn’t surprising there were artifacts after the scans. With properly preserved film negatives you could do significantly better.