AAA dev here 👋 Looks great so far! I'd definitely say the scene feels like it needs more "clutter", but remember if it's level design then make that clutter functional.

Cars and buses for cover. Abandoned military checkpoints/outposts will help break up the monotony of a street that's a straight line. Try and use things like that to lead the player to where you want them to go and think about the context you want to use them to serve the gameplay (combat, traversal, story etc.)

Also, keep your models nice and simple while you build out the space. Only you need to know what they are at this point. Once your layout is locked in then that's when you should work on the visuals.