How to cancell my pending purchase in app store

Wait for it to clear and then ask for a refund. Click on this link -->

Request a refund for apps or content that you bought from Apple - Apple Support

"If the charge is pending, you canʼt request a refund yet. After the charge goes through, try to request a refund again."

If you have defaulted on a purchase due to a denied payment method, you must speak to Apple Support to resolve this issue.

Direct link to Apple Support options -

https://getsupport.apple.com/?caller=kbase&PGF=PGF63005&category_id=SC0245&symptom_id=23362

World-wide Apple Support -

Contact Apple for support and service - Apple Support

M1 Mac mini, macOS 14.5;  Watch, series 7 GPS/cellular, watchOS 10.5; iPhone 12 Pro, iOS 17.5; TV 4th Gen, tvOS 17.5; HomePods, audioOS 17.5 and Airport Express w/ Airplay 2