Wifi or LTE?
I think the best autonomies are attainable with intensive use, with little standby. Standby doesn't add up to SoT but still uses battery. I rarely need to use the phone for more than 2h a day, using a Mac is so much more productive and pleasurable.
Anyway, battery use is pretty much the same after setting up the phone as new. around 6h SoT over 24h of standby. But it's true that I have an iMac at home, and I work from home, so maybe the phone is connecting to the Mac for continuity, and that takes a toll (no, it doesn't connect to finder over WiFi). In fact I noticed more autonomy when I was in a hotel on a trip. Food for thought.
Edit: oh, the offline mode was a Shortcuts bug. If I put manually it in airplane mode it stays so. If I automate it it didn’t work. But it did before. I deleted and created the automations again, let’s see