Answers for "how to insert circular radius in shape flutter"

using shape property in flutter for circular corner

shape: RoundedRectangleBorder(
  borderRadius: BorderRadius.circular(18.0),
  side: BorderSide(color: Colors.red)
),

flutter squared avatar rounded borders

ClipRRect(
  borderRadius: BorderRadius.circular(20.0),//or 15.0
  child: Container(
    height: 70.0,
    width: 70.0,
    color: Color(0xffFF0E58),
    child: Icon(Icons.volume_up, color: Colors.white, size: 50.0),
  ),
),