Full screen mode is macOS native tiling mode, you can put two windows side by side and use as much real estate as possible (no menu bar nor title bars)
Sorry, that really was only an example. I also didn’t say, or mean to imply, full-screen only. Every os should also let you line up windows top-to-bottom out of the box. Etc. Macos' approach of allowing one very specific combination of window arrangement, then trying to make a feature of it by calling it 'fullscreen' or 'side-by-side' (or whatever they call it) just doesn’t really cut it.