How do i turn on peak performance

If the battery health is at 80% capacity or less, then the only option is replacement.

iPhone Battery Replacement:

Current Apple Prices:

• No charge for in-warranty or AppleCare+ plan.

Out of Warranty Prices:

• iPhone X: $89 U.S. Dollars.

Click ▷ Check AppleCare Coverage.

Click ▶︎ iPhone Battery Replacement.

Need more help?

• Chat now or call 1-800-APLCARE.
• International Support.

Click ▶︎ iPhone User Guide. 📖

Good luck! 👋🏼😉

Hello! These are the steps (battery.)

Settings > Battery > Battery Health.

Hope this helps!

Viona