A portable projector, a real screen, offline movies, and enough power to finish the film.
This is the setup we use. The projector sits low and centered, the screen stands at the end of the bed, and the tent becomes a small movie room after dark. The movie: Yog, Monster From Space.
This is the projector we use, but most have similar features. USB ports are standard.

This is the screen we use. Trust us: tent walls do not work as a screen. Use a real screen.

This is the power station we use when campground power is not available.
A thumb drive keeps movies ready and removes campground internet from movie night.
Bring the movies with you. Cell signals or campground WiFi should never decide whether movie night happens.
Copy movies to a USB drive or download them before the trip. Test the files on the projector at home so the sound, subtitles, and file format all work.
Internet Archive has downloadable feature films that can be stored for offline viewing.