I have two monitors on my desktop. Both are 4K but one is set to magnification 100% and the other set to 175% for easy reading. When I run Illustrator on the 100% monitor and the pallets slip over to the 175% monitor, the pallets enlarge to 175%. Dragging them back to the 100% monitor leaves them at 175% magnification (which is much bigger than everything else).

The magnified pallet still takes up the size of the regular un-magnified pallet, but the contents are too big to work and there are no scrollbars. So the Pallet boundaries are resized, but not the contents.