Check on a refund
How to check the status of a refund request
iPhone 8 Plus, iOS 14
Question marked as
Did you check the link provided at the top left of this page? I do not know of any way other than doing that. I believe Apple will send you an email knowing of their decision when it is made. You also don't say if you are asking about a refund being granted or actually receiving money from a refund. For the latter:
How long refunds from the App Store or other Apple services take - https://support.apple.com/HT210904