Increasing the voltage doesn't require a thicker cable, and 5A power starts with 100W USB-C PD. USB-C cables that support 5A aren't that thick, but they do need

Increasing the voltage doesn't require a thicker cable, and 5A power starts with 100W USB-C PD. USB-C cables that support 5A aren't that thick, but they do need a special chip so that the devices know it's safe to send 5A.