Loosing 2% in two months is perfectly normal.
Batteries degrade over time with usage due to chemical aging, that's just how they work.
You can expect about a 1% drop per month with average use on an iPhone.
Apple recommends replacing it when it reaches 80%. To check your battery health, go to Settings > Battery > Battery Health.
iPhone Battery Replacement.
iPhone Battery Repair & Replacement - Apple Support
About Lithium Ion Batteries
iPhone Battery and Performance - Apple Support (IN)
Here are some tips on maximizing battery life.
Batteries - Maximizing Performance - Apple Batteries - Maximizing Performance - Apple