[Quoth]

Star Wars also is a Movie franchise, though there are Novelisations, and I have many books by Alan Dean Foster that are not Star Wars.

Depending on your view point Star Wars is either Space Opera or SF.

Genres are tricky. SF and Fantasy have a spectrum. Some are clearly SF and some clearly Fantasy, but Dune and Pern series are both published and recognised as SF, yet are much closer to non-SF Fantasy. It seems that if there is space travel, it's SF. Pern has implied space travel.

Post apocalyptic is usually SF, but the Shannara series gets assigned as Fantasy, and at the start it certainly isn't suggesting post apocalyptic SF, though later books certainly are.

Having magic (usually called psychic powers) doesn't automatically make a novel be SF (Dune, McCaffrey's Tower/Talents/Pegasus series, or Acorna series). Sometimes the technology is really magic by another name, but the novel is published as SF rather than Fantasy.

Zane Grey's "Riders of the Purple Sage" is published as a Western, but it's also adventure, critique of Mormons and a sort of Robinsonade. He was inspired by reading the Virginian, which is maybe the 1st famous western (and not much like the TV show).

Publishers are the main decider of genre and unless a novel clearly fits an existing (and popular genre) it won't get trad published. Many older books are not single genre like modern trad published. You'll thus find some more varied stuff in the better SP titles.

Also a novel can be an SF or Fantasy setting and really be a Western, Romance, Spy, Adventure, Detective, mystery, Robinsonade, Pirates or Mstaken Identity / Swap.