How to test REFUND notification in sandbox?

I would like to support Apple's in-app purchase using Nestjs.

I completed the information about Subscription, but I couldn't complete a refund for in -app payment products (available many times).

The above is the question I summarized.

  1. Apple (V2) is a notificationType of 'BODY.SIGNEDPAYLOD' to handle both subscriptions and refunds for in -app payment products?

  2. Is there any way to refund the products purchased from Apple on Sandbox?

Please feel free to answer just 1 question, not all of them!

Thank you for reading my questions.

How to test REFUND notification in sandbox?
 
 
Q