YES! Sanding a pearl or metallic will leave a dull silverish area that WON'T go away when you clear over it.
If you get a run or other ****er in pearl/metallic colors you can...
A) Leave it, and be more careful next time...
B) Let it dry & sand it. But then you will have silvery stuff, which requires more color to hide it. But if you only spray one area, you'll have dusty edges. Spray those with straight reducer to blend them out a bit.
C) Spray one more shot at the run, then support the frame so the sag goes back the other way. May have to flip it a few times until the paint sets a bit. Then just hit that spot with some extra clear so you can buff out the bumps in the clear instead of the color. Just don't sand through TO the color!

If in doubt, try a sample on a piece of PVC pipe.