I bought a book by mistake, meant to buy the audiobook. Request a refund for the print book BOTH/AND byHuma Abedin

Follow these instructions:

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

Note: Apple considers all sales final and refunds are made on a case-by-case exception basis.

No one here in this user-to-user forum would know what kind of decision Apple will make. Based on anecdotal evidence, if you've never asked for a refund before, it will be close to automatic. But, you won't know until you ask Apple.