1. You don’t need to do anything if you’re willing to pay for roaming.
2. Get an AIS (best coverage) SIM card if you’re a tourist.
3. For long term stay either convert your home SIM to eSIM or get a cheap phone to receive SMS.
For the US there’s some providers of VOIP that support receiving SMS too.
Through using “wifi calling” (turn it on in your smartphone) you can use your home provider as if you were at home (calls to Thai numbers are international then!) whenever you’re in a WiFi.