I should also add, I found this article: Apple Watch Battery
In this article, they came close to what I was looking for. For the Apple Watch SE, this is what is mentioned about expected battery life when 4G LTE is used.
Family Setup Battery Life
Up to 14 hours
Family Setup battery life is based on the following use: 70 time checks, 45 notifications,
20 minutes of app use, a 5-minute phone call, and a 30-minute workout with music playback from
Apple Watch via Bluetooth, over the course of 14 hours with 4G LTE connection and Find My
location sharing enabled. Testing conducted by Apple in August 2022 using preproduction Apple
Watch SE (2nd generation) (GPS + Cellular); all devices tested with prerelease software.
Battery life varies by use, configuration, mobile network, signal strength and many other
factors; actual results will vary.
It is not entirely clear how long the watch can last without a phone as there appears to be a phone nearby (bluetooth connection for music playback). I am also not sure what "Family Setup battery life" actually means.
Again, unclear. Wishing there was two statements for how long it can last without the phone when connected over Wifi and separately when connected to 4G LTE.