I get about 36-40 hours off a full charge of my Series 5 Cellular. I wear it all day and to sleep, swapping it on the charger for my trusty Series 0 for an hour or so in the mornings when I have breakfast, shower, etc.
Usually, when I put it on the charger on arising, it has 40% or so left.
During the day I use it for alerts, audio play through Bluetooth (both of on-Watch content where the Watch itself streams, and as a control for content playing on my iPhone), and pretty frequently for Siri. I have a sleep tracker app.
My settings, for those items that would appear to have battery impact:
Background app refresh: mostly on
Wake screen on wrist raise: on
Auto-launch Audio Apps: off
Wake for: 15 seconds
Workout power saving mode: off
Display brightness: slider is mid-way
Listen for "Hey Siri": off
Raise to speak: off
Haptic alerts: On, Prominent
Fall detection: On
Start Workout Reminder: On
End Workout Reminder: On
Detect Gym Equipment: On
During the day: Always-on Display is on
When sleeping: Always-on Display is switched off via Theater Mode, and Do Not Disturb is turned on
In the Dock:
iCatcher
ECG
Messages
Timer
Battery Grapher
AllTrails