As a suggestion to Adywan,

In regards to making the ground battle at Endor bigger and adding all the Rebel troop action, I totally agree. This is the final battle of the trilogy, the ground battle should be better than the previous ones (Scarif comes to mind). I suggest that you include AT-STs and even an AT-AT or two in the battle against the Rebel troops, as the AT-AT is seen on Endor but never utilized. Maybe use the 2015 Battlefront reveal trailer as inspiration?
Either way, you could add scout trooper snipers, some heavy machine gunners, and TIE bomber air strikes on top of the walkers to make the scene more memorable and stand out amongst other ground battles.

Another suggestion, this one very secondary, is to have a “montage style” section right before the Battle of Endor, showing Rebel offensives on many planets across the galaxy. This is really a way to show the true scope of the Galactic civil war.

As a final suggestion (but that is unlikely to happen) is to add a new opening scene. One of the problems with ROTJ is that people say Vader was made obedient and “on a leash”, so he wasn’t seen as dangerous as before. Well my fanboy dream would be to see Vader leading stormtroopers against Rebels in a rundown city, and watch him mow down Rebels with ease, to a greater extent than what we see in Rogue One. This would make him a lot more fearsome in the movie IMO, and be a parallel to Luke taking down dozens of Jabba’s guards. Kind of previewing the skill of two fighters before their final confrontation.