Change the shape property of the new Elevated Button

ElevatedButtonShape.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          onPressed: () {},
          child: Text('Button'),
          style: ButtonStyle(
            shape: MaterialStateProperty.all<OutlinedBorder>(
                RoundedRectangleBorder(
              borderRadius: BorderRadius.all(
                Radius.circular(30.0),
              ),
            )),
          ),
        ),
      ),
    );
  }
}

thank you very match bro, you help me a lot

valeu mano, ajudou dmsss

Glad I could help!