Most 65W chargers are 20V/3A. Standard USB cables are built to carry at most 2-3A, and e-marker cable authentication chips are required for 5A, I believe, because people running 100W on a random USB cable is scary.

Chargers that would do 5V/5A probably do PD 20V/5A as well, = 100W. Or it'll be a non-conforming special Pi PSU of sorts.