To scale widgets, we use the typical Transform.scale(), constructor. To scale up a widget, for example, we can use it as follows:

Transform.scale(
  scale: 2.0,
  child: RaisedButton(
    child: Text("scaled up"),
    onPressed: () {},
  ),
);

And to get the same result using the default Transform constructor, we use the following:

Transform(
  transform: Matrix4.identity()..scale(2.0, 2.0),
  alignment: Alignment.center,
  child: RaisedButton(
    child: Text("scaled up"),
    onPressed: () {},
  ),
);

In a very similar way to the rotation, we must specify both the origin of the transformation with the alignment property and the Matrix4 instance describing the scale transformation.