AnimatedDefaultTextStyle is an animated version of DefaultTextStyle. The widget automatically changes the default text style whenever the given style changes.
In the example below, we try changing fontWeight, size, and color on Floating Button pressed.

import 'package:flutter/material.dart'; class HomePage extends StatefulWidget { @override _HomePageState createState() => _HomePageState(); } class _HomePageState extends State<HomePage> { bool _isFirst = true; @override void initState() { super.initState(); } @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('AnimatedDefaultTextStyle'), ), body: SafeArea( child: Container( color: Colors.grey[100], child: Center( child: AnimatedDefaultTextStyle( duration: const Duration(milliseconds: 1000), style: TextStyle( fontSize: _isFirst ? 48 : 24, color: _isFirst ? Colors.red : Colors.blue, fontWeight: _isFirst ? FontWeight.normal : FontWeight.bold, ), child: Text('TL Dev Tech'), ), ))), floatingActionButton: FloatingActionButton( onPressed: () { setState(() { _isFirst = !_isFirst; }); }, child: Icon(Icons.play_arrow, color: Colors.white), ), ); } }