yogiboy0
You don’t want to put a 30A breaker on a 20A circuit.Agreed! If you are using a 20A receptacle, you want a 20A breaker.
For a 20 amp circuit 12-2 romex would be the correct gauge to use. If you use 10 gauge it will be difficult to terminate on the outlet ... 10 gauge ( 30 amp ) is used for something like a clothes dryer!There can be advantages to using 10 gauge wire on a 20A circuit, including reducing voltage drop. It is difficult to work with, and using a pigtail into the outlet does make it easier to terminate.