I opened mine in 2018 at Bangkok bank outside of the tourist hotspots. I had a tourist visa only. Just try different branches. The 3rd one said yes. Getting mobile banking working was another story..
In phuket all banks refused to open a savings account. One branch of Bangkok bank in isaan was ok. I showed them a letter from my own bank in Switzerland with a proof that Iโm a "reliable customer" take a thai person with you. Bank employee might not understand you. It was a pain to get mobile banking to work. Now i have it all. Iโm not living in Thailand yet, but if wheoi arrive, i already have a few baht there