Iphone batter capacity

It is possible depending upon your usage. To learn about maximizing battery life and lifespan, read this support document --> Batteries - Maximizing Performance - Apple

"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." --> iPhone Battery Repair & Replacement - Apple Support

iPhone Batteries on average lose from 1-2% battery health per month, depending on number of full charge cycles. Since you've owned your phone for 9 months, you are well within the range of reasonable battery health decline.