Yes, Apple will replace the battery on an iPhone over 80% if it is covered under the warranty or AppleCare+. If your iPhone is not under warranty or AppleCare+, Apple will still replace the battery for a fee. The exact cost will depend on the model of the iPhone and the region you are in. It is recommended to contact Apple support or visit an Apple Store to check the pricing and availability of the battery replacement service. It is also advisable to create a backup of your iPhone's data before getting the battery replaced.