I now have the 100 amp breaker installed in my load panel. I will run wiring from the load panel to a 100 amp sub-panel in an unground 80 schedule PVC. I believe I need to use #2 wire for the hots and the neutral. If this is correct, then what size ground do I use? Number 6? The sub- panel will be 50 feet from the main load panel.

I now have the 100 amp breaker installed in my load panel. I will run wiring from the load panel to a 100 amp sub-panel in an unground 80 schedule PVC. I believe I need to use #2 wire for the the hots and the neutral. If this is correct, then what size ground do I use? Number 6? The sub- panel will be 50 feet from the main load panel.
A 100 main circuit breaker gets #4 wire (NEC), Codes are set by the AHJ authority having jurisdiction.

Just to be clear, minimum size wire for a residential feeder is #4 Copper wire, or # 2 Aluminum wire, for hts and neutral.

The equipment ground can be #8 Copper or #6 Aluminum.

The distance is minimal, so voltage drop will not be an issue with either wire.