extension_1.dart

import 'package:flutter/material.dart';

extension StringExt on String {
  Text toH2(context) {
    return Text(this, style: Theme.of(context).textTheme.headline2,);
  }
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Column(
            children: [
              'Hello World'.toH2(context),
              'Hello 2'.toH2(context)
            ],
          ),
        ),
      ),
    );
  }
}