Brand New MacBook Pro overheating

If there is block to the airflow vents you may have overheating.

Keep your Mac notebook within acceptable operating temperatures - Apple Support

The MacBook could overheat if you use very computing intensive programs like CAD-Programms. But then the vents should start the airflow to cool your mac down. So if you don't recognise any vent activity maybe they are defect.

The vents could also don't start the airflow due to broken and faulty software. So make sure you use the latest MacOS-Version. Also make sure that you use software which is certified by Apple.

Also good to know if the vents are working and you use Siri they stop for the time you interact with Siri so that Siri can understand you better.

I also heard there was/is a problem with overheating if both USB-C Ports on one side of the Macbook are in use at the same time. I don't know if this problem was solved by a software update. If you only have one port in use at the same time maybe there is a hardware issue. It can always happen, that one part works insufficient due to material defects. Maybe you should visit the next Apple store to let somebody from the Genius Bar look into this problem physically if nothing described above works.