Correct. Air and gravity models in KSP are simple (though aerodynamics has been improved in the past years). Gravity simulation is essentially planet vs. active vessel, everything else is "on rails" and non-interacting. That means no Lagrange points, no sun-synchronous orbits, no need for station keeping.
However, mods come to the rescue. For flight, you have Ferram Aerospace Research, which gives you much more realistic (and much more punishing) aerodynamics, including all the interesting supersonic effects. For space, you have Principia, which introduces n-body physics, with all the Fun coming from it.
As counterbalanced to FAR, there is NEAR, which is FAR but the supersonic flight behaves as if it was subsonic, so it makes things a bit easier.
> I wouldn’t call it very realistic. The aero modeling is quite hacks/primitive and even the gravity is rather simplify... afaict they only calculate to the dominant object in the sphere of influence so you don’t get Lagrange points, for instance.
Perhaps this will change with KSP 2?
I mean, it’s playable, certainly but it’s realistic in the at something like Forza is Realistic. So, sorta, but no.