I know 91 percent isn’t terrible and probably considered closer to new, but I feel my battery drains pretty fast. It’s covered under AppleCare but I’ve only got a week left. I’d really like to get it replaced if not free maybe even a discount? From what I’ve read my battery needs to be in worse shape to have it replaced is this correct?
A while back, when two year contracts were a thing with US carriers, some people got the brilliant idea to abuse their AppleCare during a new Apple iPhone launch.
The idea went like this: Smash or damage the phone and then use an AC instance to have Apple replace it. Since Apple was now selling the new model iPhone their smashed iPhone would be replaced with the new model. Some people even thought this could be a way to switch to a different color.
All of them ran into Apple's policy of exchanging like for like and pretty soon these people realized that Apple doesn't play this way.
Your question is akin to the spirit of that idea. Apple is not going to replace your battery if it performs within its specifications. Nor will they give you a discount.
Unless your device is defective, you're stuck with it.
Or…smash your device and use up one of your AC instances. Of course that's unethical, but you'll get an entirely new device, not just a battery,
at a discount.