Using Sized Box to constraints the size

Widget to the list of children, you will need to change the height of the Sizedbox whenever you add a widget.

Don't

SizedBox(
  height: 20,
  child: Column(
    children: [
      Text(Hey),
      Text(You)
    ]
  ) 
)

Do

Column(
  mainAxisSize: MainAxisSize.min,
  child: Column(
    children: [
      Text(Hey),
      Text(You)
    ]
  ) 
)