::Good question! It’s one that comes up a lot with RVs.
You can wax over decals, but it depends on the product and the type of decal. If yours are glossy, a non-abrasive wax or a polymer sealant usually works fine and may add a little protection against UV fading. I’d avoid anything with cleaners or abrasives in it, since those can dull the surface or lift the edges over time.
If the decals are matte, skip the wax. It could potentially leave blotches or change the finish. In that case, a vinyl protectant like 303 Aerospace or a trim detailer is the safer choice, imo.
Whatever you use, test it on a small spot first. Decals aren’t all made the same, and how they respond can vary quite a bit. And read product labels for recommended use.
I wax around them so I don’t worry about it. No need to tape them off