What if my phone battery capacity showing 96 should i replace my battery or what please help me out

96% doesn't indicate a problem. See the following from iPhone Battery and Performance - Apple Support

A normal battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles when operating under normal conditions. The one-year warranty includes service coverage for a defective battery. If it is out of warranty, Apple offers battery service for a charge. Learn more about charge cycles.

No, you don't need to do anything. Over the coming months as you use and continue to charge your iPhone, Battery Health will continue to decline as ALL batteries lose their ability to hold a full charge over time.

When your battery goes below 80% that is the time to consider replacing the battery. Not until then.