I thought only the big theater version took arbitrary speaker positions, and the home theater version used premixed channels. But now I can't remember where I read that, so I could be wrong.
https://professional.dolby.com/tv/home/dolby-atmos/
I think most home theater systems end up mixing down to Dolby surround channels practice, of course. My receiver supports Atmos, but I still only have five speakers. :)