Yes, looks like it just goes to the highest resolution of the monitor. A friend explained it to me like this, in case it’s useful to anyone (I think other ppl are aware of this, this is probably just me never using that option in any game lol):
Windowed Fullscreen isn’t actually running in fullscreen, it’s a borderless window that takes up the entire screen. The game always uses your desktop’s current resolution, regardless of the in-game resolution settings. It stretches to fit the whole screen using the desktop resolution, which is why resolution changes have no visual effect.
Apparently, it makes switching to other apps faster, however, it might make your game run slower?