iPhone Battery Draining Fast

Apple won't replace the battery until the health reaches 80% or below, so keep me posted.

If your battery health is at 80% or below and you have AppleCare+ or in Warranty, then there is no additional charge. Without warranty, there would be a charge and depends on your model.

Find the estimate cost to replace your iPhone battery ⇢ iPhone Battery Replacement - Apple Support

Hello~ Click on below and scroll down to How much will it cost and put in your device information for an estimate…

iPhone Repair and Service - Apple Support

~Katana-San~

Go to Settings > Battery > Battery Health & Charging

What is your iPhone battery health at?