Battery need to replace

iPhone Repair and Service - Apple Support

The bottom line is that Apple does not consider that an iPhone's battery needs replacement unless it cannot keep, at least, an 80% charge after 500 full recharging cycles ... so, whether or not, you want to consider dropping AppleCare+, of course, is totally up to you.

Batteries are not covered by any warranty unless proven defective.

Yours will cost between $49 to $69.

Batteries are consumables and not covered by any warranty unless proven defective in the first year.

Problem is that I have an iPhone X and it's battery capacity has fallen to 86% but still "currently supporting normal peak performance". It's not that simple. Any telephone call, YouTube video or FaceTime call will pull the battery down pretty fast and for it's age that's expected. I've still got AppleCare+ and they refuse to do anything about it.

So, do I continue paying the $9.99 per month cost for AppleCare till I've invested the cost of an "out of warranty" battery replacement or just trade out of it for a new phone? It's a quandary for sure.