After taking the second PCR test (on the 5th day) - do you have to go straight back to your hotel and isolate till the results back or can you carry on going places?

A Thai friend has been asked to fly to BKK from Chiang Mai and pick up her 8 yo nephew who lives in Bang Na and fly him back to stay with her in CM for the month of May because he has holiday. No one is vaccinated. Can anyone supply me with official links to any requirements regarding quarantine/isolation- 1. For her arriving in Bangkok (She will need to go to Bang Na to get him. and, 2 . For the both of them when they return toCM. TIA