How to make a Google Play app with paid and free-with-in-app-purchasing versions?

I want to implement an IAP system as well as a fully paid one in my game.

There are about 8 levels in my game. I want the paid version to cost around $ 4 and in case of IAP, each level can be unlocked for 0.99 cents.

Do I have to create two separate apps (one for paid and one for IAP) or can I have both of these in a single app? The user can then decide if they want to buy the entire game or unlock a few levels using the IAP feature.