How to increase battery life again

Hello ~ Take a look here by click on the first helpful link…

iPhone Battery and Performance - Apple Support

When your battery health drops below 80% have it replaced…

iPhone Battery Repair & Replacement - Apple Support

~Katana-San~

Battery Health > Maximum Capacity will never increase. It will always decrease.

87-88% tells us that your phone is likely about a year old. Is that the case?

disha128 wrote:

It went to 87 percent from 100 percent

And it will never go back up again. Maximum battery capacity only ever goes down.