Step 1:Add get package to pubspec.yaml file:

                        get: 
                      

Step 2: Import get package in main.dart file

                      import 'package:get/get.dart';
                      

Step 3: code

                      import 'package:flutter/material.dart';
import 'package:get/get.dart';

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

class MyApp extends StatelessWidget {

// This widget is the root of your application.
@override
Widget build(BuildContext context) {
	return GetMaterialApp(
	title: 'Bottomsheet',
	theme: ThemeData(
		primarySwatch: Colors.blue,
	),
	home: HomePage(),
	debugShowCheckedModeBanner: false,
	);
}
}

class HomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
	return Scaffold(
	appBar: AppBar(
		title: Text('GeeksforGeeks Bottomsheet'),
		backgroundColor: Colors.green[400],
	),
	body: Center(
		child: Column(
		mainAxisAlignment: MainAxisAlignment.center,
		children: [
			ElevatedButton(
			child: Text('Show bottomsheet'),
			onPressed: (){

			},
			),
		],
		),
	),
	);
}
}

Step 4: add bottomSheet

Get.bottomSheet( 
                  Container(
                    height: 150,
                    color: Colors.greenAccent,
                    child:Column(
                      children: [
                        Text('Hii 1', textScaleFactor: 2),
                        Text('Hii 2',  textScaleFactor: 2),
                        Text('Hii 3',  textScaleFactor: 2),
                        Text('Hii 4',  textScaleFactor: 2),
                      ],
                    )
                  ),
                  barrierColor: Colors.red[50],
                  isDismissible: false,
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(35),
                    side: BorderSide(
                      width: 5,
                      color: Colors.black
                    )
                  ),
                  enableDrag: false,
 
                );

              

Complete code

import 'package:flutter/material.dart';
import 'package:get/get.dart';

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

class MyApp extends StatelessWidget {

// This widget is the root of your application.
@override
Widget build(BuildContext context) {
	return GetMaterialApp(
	title: 'Bottomsheet',
	theme: ThemeData(

		primarySwatch: Colors.blue,
	),
	home: HomePage(),
	debugShowCheckedModeBanner: false,
	);
}
}

class HomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
	return Scaffold(
	appBar: AppBar(
		title: Text('GeeksforGeeks Bottomsheet'),
		backgroundColor: Colors.green[400],
	),
	body: Center(
		child: Column(
		mainAxisAlignment: MainAxisAlignment.center,
		children: [
			ElevatedButton(
			child: Text('Show bottomsheet'),
			onPressed: (){
				Get.bottomSheet(
				Container(
					height: 150,
					color: Colors.greenAccent,
					child:Column(
					children: [
						Text('Hii 1', textScaleFactor: 2),
						Text('Hii 2', textScaleFactor: 2),
						Text('Hii 3', textScaleFactor: 2),
						Text('Hii 4', textScaleFactor: 2),
					],
					)
				),
				barrierColor: Colors.red[50],
				isDismissible: false,
				shape: RoundedRectangleBorder(
					borderRadius: BorderRadius.circular(35),
					side: BorderSide(
					width: 5,
					color: Colors.black
					)
				),
				enableDrag: false,

				);
			},
			),
		],
		),
	),
	);
}
}