I'd check out optimized battery charging, available since iOS 13... https://support.apple.com/en-us/HT210512 My iPhone doesn't finish charging until my alarm is set to go off each morning. Also, an out of warranty battery replacement costs anywhere from $49 to $69 to have Apple do the replacement. $0 if you're under warranty or have AC. Not a bad deal, and certainly a price that doesn't necessitate buying a new phone.