Changing package name of an android app is explained here, it is not hard, however, you may face error in the google-services.json file, but it is an easy fix and is explained in this site
How to Change Android App Package Name?
To change Package name of an android app, go to the Project window, right click on the app, then select Open Module Settings,
A new window will appear, select the Flavours tab in the window. this is where we will change the app package name
- Select Application Id in the list, and replace it with a new package name. for example. "com.myapp.new"
- Click Ok and wait until the gradle running finish.
If you meet the error
Error:Execution failed for task ':app:processAllcategoriesDebugfreeGoogleServices'. No matching client found for package name 'com.my.app.package.name.debug' Visit this link Fix no matching client found error android