Please cancel purchases that are "pending".
The merchant is still finalizing the purchase. Once that’s complete the amount may update, so it has not been charged to your bank account yet.
It would take about 1 to 3 business days in order to process.
See the following Apple articles:
View your purchase history for the App Store, iTunes Store, and other Apple media services
View your purchase history for the App Store, iTunes Store, and other Apple media services - Apple Support
How apps, content, and subscriptions from Apple are billed
How apps, content, and subscriptions from Apple are billed - Apple Support
If you want to cancel a subscription from Apple
If you want to cancel a subscription from Apple - Apple Support
If the subscription that you want to cancel is not listed
If you want to cancel a subscription from Apple - Apple Support
If you see "apple.com/bill" on your billing statement
If you see "apple.com/bill" on your billing statement – Apple Support (UK)
Request a refund for apps or content that you bought from Apple
Request a refund for apps or content that you bought from Apple - Apple Support