Your specs exceed even the recommended requirements. While I've noticed that the game is a little heavier in GPU load, especially if you're playing beyond 1080p, I haven't noticed an increase in temps. I have noticed that the loading screen doesn't seem to be optimized and may be loading with an unlocked framerate, but once you're in character selection, everything's back to normal.

Might be worth checking out what your hardware is doing while in-game. CPUID HWMonitor can give you some good insight on hardware utilization and temps while you're in-game. Not saying your issue is necessarily hardware-related, but it's good to know what/where the issue may be specifically (when are the fans kicking in, how fast are they spinning, etc.).

It could be that DLSS is putting more weight on your GPU. FFXIV seems to be using a custom DLSS library file so you can't just grab a different release from NVIDIA and drop it in its place.

Are you running Afterburner or any kind of re-shaders? What temp is your GPU and CPU idling at?