TiggyTheTerrible
My apologies for the late reply.
Well, I noticed I could toggle between 12MP and 50MP (MP means MegaPixels, but you probably already knew that) in the Pixel Camera app by going to the "pro" settings, I have not noticed that setting in the GrapheneOS camera app, but I could be missing something.
I have also not seen that setting in any other camera app as well.
However, it will turn off pixel binning. (Pixel binning will effectively combine four pixels into one, hence the lower resolution, but it will improve upon the light sensitivity)
I really like toggling between those settings and put it to 50MP when there is proper lighting like at day.
However, I am not aware of any solution outside the Pixel camera app to enable this option.