Good afternoon SrujithRao,
Welcome to the Apple Support Communities!
I understand the battery capacity on your iPhone X is currently showing 89%. The resource below will provide the details of a battery replacement program that is in effect through December 31, 2018 if you would like to have an Apple Genius or an Apple Authorized Service Provider inspect your device.
iPhone Battery & Power Repair
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.
Take care.