Has anyone tried this scenario or know how I should go about it?

I have a flight landing in BKK at 12:30AM and I want to connect onto another, but separate, national or international flight as soon as possible - as soon as 6am the same day.

If I dont leave the airport (aka sit on a bench for 6-8 hours) am I subject to PCR test/quarantine rules? Or does leaving the secure side of the airport to check in with the new carrier subject me to all the rules as if I was staying in BKK? Am I able to stay on the secure side to transfer to air asia or thai airways for example and not need PCR/quarantine if I am just using it in transit with unconnected tickets?

Thanks!