If you look in battery and device care.
Tap on battery and then the graph
You will see what is using the battery the most.
Could be if you've just got the phone. Part of the software learning and battery conditioning. You may experience inconsistent battery life for a few charge cycles
Also try optimising the phone regularly. I set my phone for once a day.
Restarting frequently helps clear out temporary data.
Should you still be experiencing issue after a week or so.
You may have something loaded on your phone that's running in the background constantly
Try clearing the Partition Cache, should sort that out
