Flutter responsive design: Dynamically change Column to Row if the screen is larger

Row and Column share a common parent called Flex that takes an axis direction. Simply by changing the value of direction you can change a Flex into either a row or a column.

To get the screen width you can use MediaQuery.of(context).size.width.

Your widget should look like this:

@override
Widget build(BuildContext context) {
  bool isScreenWide = MediaQuery.of(context).size.width >= kMinWidthOfLargeScreen;

  return Scaffold(
    body: Flex(
      direction: isScreenWide ? Axis.horizontal : Axis.vertical,
      children: <Widget>[
        ...
      ],
    )
  );
}