I have almost the same laptop (PS63 8M, without any nVidia dGPU).
One of the issues I had to solve was the touchpad spamming interrupts after waking up from sleep. It would keep one core at 100% indefinitely, keeping CPU frequency (and temps) quite high and burning through the battery.
This behavior seems fixed on modern kernels since I’ve installed Fedora recently and didn’t have to do this workaround, but you can still check if this still applies to you.
You might also check if you can disable the dGPU in the BIOS (can’t check since I don’t have one), and/or play with power profiles either through Gnome or tlp (lower power profiles will make your laptop very sluggish though).
Maybe check if both your fans are running. I had to replace one of mine that was starting to fail a year ago.
Other than that, I’ve never had any overheating issues with this laptop.