A 200MP sensor has been created by Samsung the "ISOCELL HP1" and from what I can tell it is rumored that the Motorola Frontier 22 will have it later this year. The sensor itself supports 2x2 50MP and 4x4 pixel binning 12.5MP photos for low light.
I agree that the file sizes will be insane, my guess is the higher MP count is also needed with the algorithms to support the massive zooms that some phones like the 20, S21 and S22 can do. Even if you look at the differences in how the phone handles the really zoomed in images and more resolution probably helps "fill in the blanks" as opposed to a straight lower MP sensor. (not 100%, but that is my best guess because I wouldn't see any other reason for such large photos)