Hello this is Faith using the latest version of iOS, how can I bring back my battery health to 100

You can't, sorry.

The deterioration of a lithium battery is due to many factors, even the age of the battery itself, as you can read in this support article that led you here.

The battery can NOT be restored to its original capacity. Start worrying when that percentage is close to 83-80%, since the battery could have unpredictable behavior.

Regards

Giulio

Faithninah8 wrote:

How to bring back my battery healthy to 100

By replacing it with a new one.

Batteries start life at 100%, a level to which they do not return.