Get a New Battery from Apple
Another reason that people gravitate toward new iPhone models is that the battery life on their old iPhone starts getting worse, and they don’t think there’s anything they can do to fix it. Remember that batteries do wear out over time no matter what. But fortunately, you can replace them!
Apple has recently cracked down on third-party and used batteries, so your best option (by far) is to go to an authorized Apple service like an Apple Store or Best Buy, and ask for a brand new battery replacement. It’s a far more affordable option than buying a new phone and can give your phone years of extra life.