The Bundle app data storage option allows you to include previously exported app data inside the generated APK. This app data will be set as initial / default app data when starting the app after installation or when clearing the app’s data. This means you will be able to generate an APK, which already ships with your preferred settings, configurations or possibly login sessions, cookies, etc.
There’s also an option to restore the initial bundled app data every time the app is started. It’s a bit like Incognito mode but with custom app data instead of no app data. To get this to work correctly make sure to fully terminate the app by swiping it off the app overview screen (otherwise the previous instance of the app may still be running in the background).
Note that you can only export and bundle app data from cloned apps; you cannot export app data of original apps.