How to tame laptop fan noise

We’ve installed Manjaro/KDE on a System76 Oryx Pro with hybrid optimus intel/nvidia gfx and all seems to be going well except the GPU fan seems to be on all the time. I think we basically want to “underclock” this machine so it runs as quiet as possible and not sure of the Manjaro tools needed to do so, if at all possible. I know this is mostly a hardware issue but can anyone recommend any Manjaro/KDE tools to investigate and possibly tame the GPU?