import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark(
        useMaterial3: true,
      ),
      home: Scaffold(
        body: Center(
          child: FilledButton(
            style: ButtonStyle(
              fixedSize: MaterialStateProperty.all(const Size(80, 80)),
              shape: MaterialStateProperty.resolveWith(
                (states) => RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(
                    states.contains(MaterialState.pressed) ? 20 : 50,
                  ),
                ),
              ),
            ),
            child: const Text('Button'),
            onPressed: () {},
          ),
        ),
      ),
    );
  }
}