Link to the kit I used: https://amzn.to/3O2AFBD (Amazon affiliate)
I used the one above because I had it available but I would recommend trying the one below, or maybe browsing your preferred website and checking the reviews to see what is best for you
3M Headlight Restoration kit: https://amzn.to/3aC6uDB (also Amazon affiliate link)

Demonstrating how to use a headlight restoration kit to restore your headlights on my E39 BMW 5 series from 2001, 520d model