The Screen Size is one of the Screen Properties in Dev Studio Alphatech Technology app builder which defines the size of the app’ screen. Nowadays, the devices come in all shapes and sizes, so your app's layout needs to be flexible. That is, instead of defining your layout with rigid dimensions that assume a certain screen size and aspect ratio, your layout should gracefully respond to different screen sizes and orientations.
By supporting as many screens as possible, your app can be made available to the greatest number of users with different devices, using a single APK. Additionally, making your app flexible for different screen sizes ensures that your app can handle window configuration changes on the device.
See below the Screen Size predefined in Alphatech Technology app builder:
It's important to test your app on a variety of screen sizes so you can ensure your UI scales correctly. If you don't have access to physical devices for all the different screen sizes, you can use an Emulator to emulate any screen size.