Version: 2021.2
APK expansion files in Unity
Create the patch APK expansion file

Create the main APK expansion file

To create the main APKThe Android Package format output by Unity. An APK is automatically deployed to your device when you select File > Build & Run. More info
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expansion file for your application, indicate to Unity to split the application. For information on how to do this, see Splitting the application binary.

Now when you Build the application, Unity generates the APK and the main APK expansion file then copies them both to the output directory. Unity uses the name of the application followed by .main for the name of the APK expansion file. For example, if the application is called my-app, the APK will be my-app.apk and the APK expansion file will be my-app.main.obb.

If you select Build and Run, Unity installes both the APK and the APK expansion file on your device. If you select Build and want to install the app manually using the ADBAn Android Debug Bridge (ADB). You can use an ADB to deploy an Android package (APK) manually after building. More info
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utility, you must first install the APK and then copy the APK expansion file into the correct location on your device. The APK expansion file name must correspond to the format that Google requires. For more information, see expansion files.

If the application starts and it can’t find and load the APK expansion file, only the first SceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
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is available. In this case, you should attempt to download the APK expansion file. For more information, see Download process.

Additional resources

APK expansion files in Unity
Create the patch APK expansion file