@ScienceX  Open NVIDIA Control Panel and go to the Configure Surround/PhysX section.  In there you'll see a diagram indicating which GPU controls each active display.  For displays controlled by the Intel GPU, the NVIDIA GPU can step in only for intensive work as you're describing.  That tech is called NVIDIA Optimus.  But for any displays wired to the NVIDIA GPU, then the NVIDIA GPU will be active all the time.  A very small number of systems offer a BIOS option that allows you to choose which GPU has direct control of the built-in display and/or the display outputs.  The Precision 7000 Series systems offer this, and the XPS 17 9700 does when configured with an NVIDIA RTX GPU.  But to my knowledge Alienware systems don't offer this.  So if the display where you want to use the Intel GPU is shown as being controlled by the NVIDIA GPU, then you can't use the Intel GPU at all.

This isn't a true hybrid system.  Since it supports GSync, the nVidia GPU is hardwired to the display panel -- the Intel GPU cannot be used to drive the internal panel.

You should have the option to use the Intel GPU with an external monitor connected by displayport or thunderbolt, though, of course without GSync.