I can tell you, when I got my pixel 6a, I immediately put GOS on it, didn't even use it for half an hour without. After that I had the phone in airplane mode for a few weeks before I started using it.
I am coming from a 5 year old LG V30 with a 3000mAh battery (original ROM). I used the phone very lightly compared to other people, and charged it once maybe every 4-5 days on average in these 5 years.
Comparing the two of them in airplane mode (even though I didn't actually test with careful attention) I felt that the LG one actually lasts equal or maybe longer. That's just ridiculous. This is WITH GOS on the pixel which means it probably uses less battery than default.
So, indeed I feel like this is the worst battery life I've experienced on a any phone ever. The Tensor is really garbage in this area.
Also yes, the cellular network connection double the battery use. Wifi doubles that too.
I'm a light user, but I feel if I was the regular user who has their wifi and bluetooth on all the time and actually "uses" his phone for "things", then this phone won't make it a full day.
Just a note, the battery will live longer than 500 cycles. Just treat the battery right. Read this post.