As a Black woman in a touristy area of Thailand, most Thai people smile when I smile at them.
Some just stare even if you smile at them (it’s probably because they aren’t used to seeing many of us in real life and I’ve also heard that some Thai people don’t talk to people they don’t know or don’t see on a regular basis)
Most people might stare/glance/take a peek at you because they are curious but look away when you notice them (they tend to mind their own business like people in most major cities in the world, but again, they are still curious about us.)
They tend to really like our hair though (they will literally point to your hair and give a thumbs up lol), especially if it is big and curly.
If you plan on relocating here, chances are you will be able to make friends with people in your building or in your neighborhood after they see you around a few times. They also like to practice a few English words and teach you a few Thai words at the same time.
I haveeee had one instance where a Thai shop keeper came out and stood right behind me at a pop up shop in a mall ( I guess she was racially profiling me because she didn’t do that to any of the white tourists who visited her table before me, and obviously I left immediately after noticing the weird vibes) but that was the only occurrence that I have experienced and I have been here for a few months now.