Flutter fullscreen

Can you try this code? You can change the code as per your need.

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:window_manager/window_manager.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await windowManager.ensureInitialized();
  windowManager.waitUntilReadyToShow().then((_) async {
    await windowManager.setFullScreen(true);
    await windowManager.show();
  });
  runApp(const MainApp());
}

class MainApp extends StatelessWidget {
  const MainApp({super.key});

  @override
  Widget build(BuildContext context) {
    fullScreenToggle() {
      windowManager
          .isFullScreen()
          .then((value) => windowManager.setFullScreen(!value));
    }

    return CallbackShortcuts(
      bindings: <ShortcutActivator, VoidCallback>{
        const SingleActivator(LogicalKeyboardKey.f11): fullScreenToggle,
        const SingleActivator(LogicalKeyboardKey.escape): fullScreenToggle,
      },
      child: const MaterialApp(
        home: Scaffold(
          body: Center(
            child: Text('Hello World!'),
          ),
        ),
      ),
    );
  }
}