Lots of things eat battery power. Couple tips:
Turn off / restart phone once per day - this may help with the apps you don't know you are running
Once per week let battery drain well down to near empty, recharge to 100% on wall charger - not computer.
Have good wifi signal, if wifi is poor you may burn extra juice.
Have
someone that really knows these do multiple full backups on different devices, wipe phone to factory, restore from backup.
Many many variables come into play that influence battery life. A 5S not two years old should not be too bad.