I’m speaking from experience. I left Sydney for Thailand on a repatriation flight (as I’m half Thai) in May and I was told by Thai embassy staff upon checkin in Sydney which hotel I was going to put up in. Ended up being Ambassador Hotel in Jomtien. However, it’s possible the process might’ve changed over the past 6 months
Luck of the draw really. People on the same flight might be quarantined within the same city but at different hotels. Embassy staff should be able to tell you upon checkin.