It's a lovely funny feature of One ui i.e. AR zone. After setting AR emoji in calling background the size of emoji should be auto adjusted because upper body of emoji hides back of caller's photo. Besides emoji other some reflections/relating calling images would be appropriate.
Also any other new on screen call receiving types may be added; like a drawing of tick mark/straight line gesture inside the receiving/decline options (in settings on/off as 2nd feature) as swiping option misses sometime for its direction side.
