FocusNode

Screenshot:

You can do that without using FocusNode or FocusScopeNode.

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Column(
      children: <Widget>[
        TextField(
          decoration: InputDecoration(hintText: "TextField A"),
          textInputAction: TextInputAction.next,
          onSubmitted: (_) => FocusScope.of(context).nextFocus(), // move focus to next
        ),
        TextField(
          decoration: InputDecoration(hintText: "TextField B"),
          textInputAction: TextInputAction.next,
          onSubmitted: (_) => FocusScope.of(context).nextFocus(), // move focus to next
        ),
        TextField(
          decoration: InputDecoration(hintText: "TextField C"),
          textInputAction: TextInputAction.done,
          onSubmitted: (_) => FocusScope.of(context).unfocus(), // submit and hide keyboard
        ),
      ],
    ),
  );
}

How to shift focus to the next TextField in Flutter?Stack Overflow