This article explains how to buy eBooks on your iPhone or iPad using the Books app in iOS 10.0 and iPadOS 13 or later. It includes information about reading eBooks, and tips for getting samples and free books.
How to Buy Kindle Books on iPhone or iPad
Buying eBooks through the Books app is easy. Follow these steps to start building your eLibrary.
Find and select the eBook you want to order to open the information screen.
Tap Buy and then confirm the order to purchase the eBook.