Boarding to a separate flight without leaving customs

Hi.

Is it possible to buy two separate one way airline flights, like USA - Guangzhou , Guangzhou - Thailand and board the second one without leaving customs IF:
A) I only have a carry on luggage
B) I've printed my boarding pass for the second flight or did mobile check in after arrival right in the airport without leaving the transit area and got a QR code and no luggage to pick up? Is 2 hrs enough for such procedure if the first flight arrives on time? I basically just have to find the gate, no?