For Android:

1. Open Your Android folder in android studio.
2. Now wait until your gradle build

3. Now click on app -> New -> select Image Assets

4. On pop-up will appear in that select you app icon image path in Foreground Layer

5. Resize icon as per your requirement.

6. Now click on Background Layer tab, and select background color as per your requirement.


7. After set background click on Next button.
   


8. Now click on Finish button.
   


9. After finish process, run app again.

For IOS:

1. Open Xcode
2. Click on Megabot -> Megabot -> Images.

3. Give images as per resolution provided in box.

4. Provide all the images.
5. After finish process, run app again.