How do I configure free trial as extra item on paywall? I need code snippets

Hi,
How can I configure a free subscription / version in RevenueCat that is an extra IAP item? 
This item should be available for free for one week. And what do I need to configure on Appstoreconnect? introductory offer?

So the goal should be that the customer can test the app one week for free and after the one week he gets the view again where he is asked to close the subscription.