The extensible display can effectively double its size through the use of a crown that also activates the rotating mechanism, plus the touchscreen supports S Pen inputs. There is an under-display camera and a suite of sensors, as well, so this type of device could soon replace a smartphone.
https://www.notebookcheck.net/Samsung-patent-reveals-a-Galaxy-watch-with-rotating-and-extensible-display.584089.0.html