Flow Layout in flutter example

Use Wrap instead of Flow.

Flow is for more complicated custom layout. Wrap is what is used to achieve the layout in your screenshot.

Wrap(
  spacing: 8.0, // gap between adjacent chips
  runSpacing: 4.0, // gap between lines
  children: <Widget>[
      Chip(
        avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: Text('AH')),
        label: Text('Hamilton'),
      ),
      Chip(
        avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: Text('ML')),
        label: Text('Lafayette'),
      ),
      Chip(
        avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: Text('HM')),
        label: Text('Mulligan'),
      ),
      Chip(
        avatar: CircleAvatar(backgroundColor: Colors.blue.shade900, child: Text('JL')),
        label: Text('Laurens'),
      ),
  ],
)

In Flutter wrap is batter widget for creating layout like your screenshot

Wrap : It can adjust its children according to the space available to it on the Screen. The default arrangement is horizontal (like a row) but you can make it vertical (like a column).

chip : This widget use for create TAG or chips

new Wrap(
  spacing: 5.0, // horizontal gap between chips
  runSpacing: 2.0, // gap between row
  children: <Widget>[
      new Chip(
        label: new Text('One'),
      ),
      new Chip(
        label: new Text('Two'),
      ),
      new Chip(
       label: new Text('Three'),
      ),
      new Chip(
        label: new Text('Four'),
      ),
  ],
)