If you are looking for ways to update your app icons to a different color, you have been updated with the iOS 14. The new Shortcut isn’t available on the previous versions and the only option you really can change the color scheme is through the native settings. Through the native settings, you can change the color scheme to either Grayscale or Inverted Colors.  To change the app icons to the above-said modes you can refer to the tutorial mentioned above for devices that are not updated to iOS 14.