A free program for Android, by Smart Theme.

Samsung A21s Launcher is an app for Samsung Galaxy A21s smartphone that lets you change the look of the phone with an awesome theme, HD wallpapers, and more.

How to Use Samsung A21s Launcher:

Download and install the app on your device. If you have Android 6.0 or above, then you can start the installation by selecting the APPLY button. If you are using Android 5.0 or below, then you need to first enable the optional installation of the app. To do that, open the settings menu of your device, and then select the INSTALL option.

Once the installation is complete, open the app and you are ready to use it.