Issue renaming existing expo application

I am new to react native and I want to rename the project name and its package name I gone through this

https://github.com/expo/expo/issues/1946 -- according to this I changed the app.json.

Expo {
   name: something 
}

Change package name for Android in React Native - according to this I installed rename package but got below

A directory should be created using "react-native init"

And I also want to know how can I check my app package name while using expo as it won't have an android/ios directory.

Both are not showing the expected result. please help.