A:Answer It depends on what you play. With Rocket League on 120 FPS and max settings, I was getting mid-70s temperatures. That was with undervolting. Otherwise, I'd get mid-80s and even a bit higher. Check out the Intel XTU tool for undervolting, and read some guides on how to do it. It's perfectly harmless. It lowered my temperatures as much as 15 degrees in some games. Usually, I'd get maybe 10 degrees savings, though.
I think it helps that this model has only a GTX 1060. It doesn't run as hot as the 1070 or 1080. The full Zephyrus M does not have a Max-Q 1070, so it will run hotter. Also, this model does not come stock with an NVMe SDD. It is M.2 SATA. NVMe runs significantly hotter due to its high speeds. It's actually a good thing ASUS only provided an M.2 SATA, as an NVMe really needs a dedicated fan to not overheat things. I know that people with last year's full Zephyrus model were reporting battery bulging and meltdowns due to the NVMe SSD being right next to the battery. In this model, it is the HDD that is next to the battery, and the M.2 SATA SSD has some space away from the battery. That is a very, very good thing.
If you choose to replace your M.2 SATA SSD for more storage, I highly recommend you stick with M.2 SATA instead of going NVMe. Unless you do video editing, you aren't going to notice much of a performance gain anyway. You will, however, keep your laptop cooler with the M.2 SATA. And, you might just prevent a battery bulge/meltdown.