Is it possible to change product quantities during the checkout process?

Changing product quantities during the checkout process is typically not allowed in Magento. The primary function of the checkout process is to finalize the purchase, and any adjustments to product quantities should ideally take place in the shopping cart before the checkout begins.

The cart serves as a preview of the items the customer is about to buy, allowing them to make final adjustments to quantities or remove items from their order. Once they proceed to checkout, the expectation is that they have already confirmed what they want to buy, so the quantities are effectively locked in, ensuring a smooth and efficient transaction process.

This functionality helps to prevent confusion and enhances the overall user experience by streamlining the checkout phase, making it clear that all quantities should be verified before moving ahead with the purchase. Thus, the assertion that changes can only be made in the cart aligns accurately with standard practice in Magento, reinforcing the correct answer.