Surprisingly, the contractors retain copyrights and trademarks somehow. For example, apparently you need a license to put an f-22 or an f-35 in a game (or movie etc?), I think those things necessarily belong to the taxpayers. Weird licensing.
As for licensing to put the f-22/f-35 in a game/movie, I wonder how much of that is actually needed from a legal perspective, and how much is "lets just do it anyway".
The name is covered by trademark so you need a license to call it "F-35 Lightning", but I don't think the design or shape of an aircraft is covered by copyright or trademark law, so it should be fine if you just avoid the name.
[1] https://www.nationaldefensemagazine.org/articles/2016/9/8/in...
There is a separate regime that covers useful articles: design patents, which have a much shorter term. The design patents can AFAIK cover things like toys, I don’t know about game assets. You might have to look at the actual grant of patent rights to see what is claimed. I don’t get the impression that the big aircraft manufacturers care about games for plane nerds.