Go big and epic. Its Star Wars.
1 big world + smaller sized ones.
The smaller size ones can be the size as KOTOR planets. Have a town/ hub, main NPC area or 2 in each planet + Side quests.
Lots of lore and options to do stuff, from bouty hunting, Jedi/Sith training, Temple ruins, chilling in a Cantina, playing Dejarik ( Star Wars chess )
Your customizable space ship as the main Hub for character and crew
RPG Elements, lots of NPC and optional addable crew members. Romance, friendship and helping them out with there story/quests
Choices to go light or dark side like KOTOR
Combat like Sekiro or Ghost of Tsushima. Focusing on Light saber forms. + 3rd person shooting and gadgets, if your not a Jedi.
NPC and Quests like Witcher 3, KOTOR and Mass Effect + Optional discreet side quests like DarkSouls/Bloodborne
Add in a couple of Uncharted 2 like missions for that roller coaster action packed adventure