If you're going to go through the hassle of sanding down your headlights then as I mentioned in a previous post, you might as well apply PPF protection to the headlights afterwards. Not only will you get UV protection but you'll protect them from scratches and road debris which will also cause hazing in the future. Plus you don't have to worry about high grits or the clear coat not adhering to the headlight. Just sand them, wax and buff them and then apply PPF
some reference links below (no affiliation)
https://ceramicpro.com/the-ultimate-...otection-film/
https://www.3mcanada.ca/3M/en_CA/p/d/b40066727/