I’m thinking of writing a campaign in the style of World War Two it would borrow elements from the clone wars but it would take place in a “modern” settting. Any critiques and tips would be helpful and welcome.

Reading a book on the end of WW II now. Mostly about Japan and they struck out in search of steel and oil. They saw the USA as inhibiting them, basically with an embargo. They felt forced to lash out (from their perspective). The other half of that is the atrocities they committed against conquered peoples. Racial superiority. Some really heinous stuff. But for a SW campaign, maybe the quest for resources would work best. As far as the Germans go, they never got over the Treaty of Versailles. They wanted back the land and power it deprived them of. You could easily have 1) a planet that lost a war an age before, but now feel unjustly treated and want to reassert themselves, or 2) a planet who wants (or lost....or claims a) territory, resources, or power and want to take it. Maybe that's a bit Neimoidian-like, but it'd fit. I assume you are talking about a system or planet and not the universe, as a whole.

Star Wars kinda is WW2'ish but where the Axis won and now there is a rebellion. If you want a more WW2 experience then the Clone War period is the actual war. So the changes you would make would be that there is no Rebellion, though there would be resistance groups like the French in Europe, it's actually an all out war between relatively equal military powers. Your PCs would be soldiers or spies, or resistance members. Your adventures would be attacking military targets, defending the same, front line combat, secret missions behind enemy lines, gathering intel, saving VIPs, etc.. The main feel though would be mission based and in uniform as your PCs would likely be soldiers not rebels, and it wouldn't be about hiding from the Empire but confronting it directly. The war would big and all around you and PCs would always have the possibility of being caught in some major battle. Think Wonder Woman and Captain America, a group of special characters doing heroic things while the war rages on around them.

I wouldn't have the war just about resources or territory. Those may be the main reason for most wars but then you strip the heroic nature of the characters actions, they become tools to get stuff rather than heroes overcoming an evil. Germany may have been primed by the economics of losing WW1 but the true evil was the racial superiority ideology and ruthlessness of the Nazi regime. Same goes with the Japanese, they may have needed the resources but the driving force was the belief that it was time for history to revolve around Asians and the Japanese believed they were the superior culture that was going to make this change. Basically there is lot of evil to work with that is much more compelling than fighting over Hyperfuel and planetary systems.

Take a look at Achtung! Cthulhu there is a lot of good material there that you can re-skin.
https://www.modiphius.com/achtung-cthulhu.html