Battery health is not good

You have not said what your Battery Health is, but you need not worry until it reaches 80%, at which time you will need to make an appointment at an Apple Store for Battery Replacement. Check this link...

https://www.apple.com/batteries/maximizing-performance/

Batteries are meant to degrade over time, which means after a while they won't hold the same battery capacity of which they used to.

Try going into Settings > Battery > Battery Health > What % are you on? Anything below 80% is a cause of concern. Apple recommend it should take around two years of usage to reach that level

You might also find this helpful as it provides you with useful information on maximising your battery.