Yeah, Arma 3 was in my list initially (particularly 2019 DLC Contact). Didn't remember why it is not here anymore. I've playmed ArmA 2: DayZ Mod back in 2013 and that was impressive.
I second this. I disagree about Squad being any really good looking compared to Arma though. Up close Squad looks great, great effects but beyond that it just looks bad and washed out. Also there is this "plastic" look about it (just like Post Scriptum) which is just wrong for realistic kind of game. Besides both Squad and Post Scriptum are EXTREMELY limited in what they offer gameplay-wise - MP only, small maps, no destruction, basic medical system, few modes, just few vehicles, few weapons, there is SO little content.
Compare Arma and Squad for yourself.
Also to add to recommendations - Metal Gear Solid: Ground Zeroes / V: The Phantom Pain looks great (especially the lightning and models).