Apple can be very picky with repairs if there are other hardware faults. They may want to sting you for a new screen and battery, but they may not. Best to visit the "Genius bar" and hear it from the horses mouth.
If there is any physical damage to the device, Apple will make you have it repaired before they will do the battery replacement.Just wondering as i got an iPhone 8, for 100 USD, battery life 90%, but I want to know my options of battery replacement since Apple also replaces the waterproofing strips when they replace the battery.