I had the same pc before, then I got those massive frame drops. It also dropped to 30 after a while. This is why i got a Xbox series S being less than a half price of my pc i get 140+ fps lowest it gets is 120
But its a h series processor so maybe that's why... But yeah I'm planning to change the thermal paste for the cpu... Soon. And yeah, the gpu temp. is alright I guess considering my room temperature.
It's not the thermals but thr Optimus being enabled on the laptop. You need an external monitor connected directly to your GPU which you can check what port it uses on NVIDIA Control Panel, only then can you use the full performance of your laptop.