Based on recommendation, I had done a base of xpel film and top coat of opticoat pro +
Applicators suggest ceramic on top of the film.
However, do to more extensive film coating later on, the opposite sequence was done on other parts of the car.
This was 4+ years ago, both application sequences still look great, but the film is much easier to clean with the ceramic on top.
The question is what happens when you remove the film...
Ceramic on top: you need to reapply
Ceramic on bottom: if it stays and is not damaged when the film is removed , then you save a reapplication