Stay out of movie theater. Usually, there will be good hi-fi stereo speakers in theater
and it is no good to your ears regardless good earplugs.
In a way I agree with you but it all depends how sensitive one's auditory system is. A person can use the best custom made earplugs available but they will not help in the slightest if external sound is too loud, because it can pass through the skull and reach the inner ear by bone conduction.
A person that has noise induced tinnitus. If they have not habituated I advise not go to a cinema. If a person has habituated and has no hyperacusis and wants to go to the cinema, I advise wearing noise reducing earplugs but keep in mind what I've mentioned above and be careful.
Michael