Don't game on the battery it will just kill it as the power draw is so high. Use the ASUS Battery Health Charging to minimise battery wear, set to 60%. Turbo/OverDrive being disable on battery is perfectly normal.
For the temperature, raise the rear or place the notebook on a cooling pad. ThrottleStop can help by undervolting the CPU which will reduce temperatures. I have the previous GL703GS; it can spike as high as 95C, however under sustained CPU load it will hold below 80C
Here both Prime95 & CineBench R15 are running CPU is in the mid 70C region, ambient being aprox 25C/26C. You can use HWinfo64 to see the average temp when gaming, just reset the values prior to starting a session. If the game does not need maximum performance then limit it, GL703GS has a TDP down feature or Turbo limits can be reduced in ThrottleStop.
IMO the cooling is pretty decent, although it can be improved with very little work. Here CPU PL-1 is unlooked and reset to 65W
This a massive load for the CPU under Prime95, equally no thermal or power throttling, as the cooling solution is keeping up. Beyond a sustained 65W the chassis is not capable of keeping up, nor do I recommend unlocking Turbo limits unless you no exactly what your doing, however it does illustrate the notebooks CPU cooling capacity. Under normal use the CPU is allocated up to 90W for the first 28 seconds of boost (PL-2) then will drop to the default 45W (PL-1)
GL703GS, 8750H, 32GB @ 2666, GTX 1070, NVME & SSHD, -140mV undervolt applied via ThrotttleStop, stock thermal paste, W10 Pro 1809
Q-6