You can pretty much do anything to a window in KDE Plasma: you could force it to stay behind, force some arbitrary state or geometry upon it, add a setting that

You can pretty much do anything to a window in KDE Plasma: you could force it to stay behind, force some arbitrary state or geometry upon it, add a setting that hides it from the apps bar, or even from the alt-tab list - or you could do all of this, it's just a couple clicks away under the window title bar icon, other actions, configure... I'd wager to say you have much more control in KDE than in any other DE, macOS and Windows included.