I noticed something about the posters used for different Star Wars movies, and the way the films are therefore marketed.

The main posters for the original trilogy use title cards emphasizing the title of that specific movie. In the example below, "Star Wars" appears in the corner above the film's main title, "Return of the Jedi." Note how the Episode number doesn't appear at all, though in the theatrical release, the title crawl denoted Return of the Jedi as Episode VI. I think the fact these movies were also "Episodes" just added to their weird allure, as the trilogy felt as if it was but a mere glimpse into a vast galaxy, and we were lucky just to see one small part of the many stories it had to tell.
https://image.tmdb.org/t/p/original/jQYlydvHm3kUix1f8prMucrplhm.jpg

The main posters for the prequel trilogy strongly emphasize the Episode number. People had spent so long with Episodes IV-VI, wondering what Episodes I-III might contain. The film's unique title is still featured prominently, but the first thing I read when I glance at this poster is "EPISODE III." I can kind of feel just how much hype that would have created back then, finally filling in those missing episodes.
https://image.tmdb.org/t/p/original/xfSAoBEm9MNBjmlNcDYLvLSMlnq.jpg

The main sequel trilogy posters use a title card emphasizing the franchise. STAR WARS. Fans were desperately aching for another great Star Wars movie, and Disney had spent a lot of money on that brand. Episode numbers again aren't featured, and the film's unique title is featured with less prominence than with any other Star Wars trilogy. The first thing you're meant to see is STAR WARS.
https://image.tmdb.org/t/p/original/db32LaOibwEliAmSL2jjDF6oDdj.jpg

If you're curious about other Star Wars entries, spinoffs generally feature the film or show's main title the most prominently, with a couple exceptions.