Keep the icons name as it is right now, While creating new icons rename the icons name as it is and upload it to the assets folder. If you do so you need not worry about anything.
For android: rename your image to android_launcher.png. Recommended size is 433 X 433 px
For iOS: rename your image to ios_launcher.png. Recommended size is 1024px X 1024 px
Once you have replaced the images and renamed it as it is, just run these commands to see the changes
open terminal
run the command below
flutter pub run flutter_launcher_icons:main
To change the App Logo if you decide to change the name of the image, follow the following steps
open your pubspec.yaml
upload the desired image and set the path to image_path under flutter_icons
After that open terminal
run the below code
flutter pub get
flutter pub run flutter_launcher_icons:main