A new optional overlay scrollbar floats over the document. It shows as a thin bar when you move the mouse, gets thicker on hover and hides on its own, so the document can use the full window width. You can drag it, click the track, and hold the mouse down to scroll repeatedly. Turn it on by setting the Scrollbars advanced setting to smart, or with the Change Scrollbar command (CmdChangeScrollbar).
Scrollable home page thumbnails
The recently opened documents thumbnails on the home page scroll, so you can see more than one screen of them.
Snap layouts on Windows 11
Hovering the maximize button shows the Windows 11 snap layouts menu.