how to make a full round button flutter code example

Example 1: flutter button border radius

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

Example 2: how to change the shape of a buton in flutter to cicular

RawMaterialButton(
  ...,
  shape: CircleBorder(),
)