It seems that several complaints over the Xbox Series S is running hot. The console runs warm with any of serveral AAA titles including Halo: MCC, CoD: Zombies, NBA 2021 and others. It seems that after a few hours of gaming, the console is very hot.
Some found a stand for the Xbox Series S and controllers allowed the console to not run as hot. Most likely this will become the norm for those who use the console heavily.
The Xbox Series S is smaller than the Xbox Series X. There is a cooling fat but placement has to be aware of the need for good air flow. The TDP can be fairly high when playing demanding games even at 1920×1080 which is what the machine is best at. Playing games at 3840×2160 is where the thermal load really gets demanding.
Do not run the console on a carpeted floor. Keep it on a media stand beside or under the television. Make sure its well ventilated.