Icon Kitchen is an easy way to create icons for your apps and then flutter icon launcher is a nice package to use the icons that icon kitchen makes and generates all the launch icons for your app.

1. First you want to install the icon launcher and build runner

flutter pub add flutter_launcher_icons dev:build_runner

The build_runner package provides a concrete way of generating files using Dart code. Files are always generated directly on disk, and rebuilds are incremental

2. Add this config to your pubspec.yml. This will tell flutter_launcher_icons what icons to build and what to use for the image

flutter_launcher_icons:
  image_path_android: "assets/app_icons/android.png"
  image_path_ios: "assets/app_icons/ios.png"
  android: true
  ios: true
  min_sdk_android: 21

3. Create your icon! Icon Kitchen. Once you’re done, add the image to your assets/app_icons/ folder

4. Run dart pub run flutter_launcher_icons and it should generate all of your app icons. Clean your project with flutter clean and then launch your app and you should see the new icons on the home screen