Should I use rgb or cmyk for lightbox advertising?

CMYKRGB can also be used for inkjet printing but there is a color difference. It is mainly used for light box cloth, general slogans and outdoor large-scale wall advertisements;

The inkjet printing of that kind of material uses oil-based ink for outdoor printing. Use photos to separate indoor and outdoor areas, usually using adhesive tape, posters, and light sheets. These materials, such as the advertisements and display racks posted on the counters of shopping malls, all use real ink paintings to capture indoor photos.

Generally, it needs to be coated, mainly solid light film and sub-film photo film, there are very few of them.