Based on my recent experience with a Librem 5, this is an accurate figure if anyone has doubts. Not doing much with the phone, just a few (like 4) photos and SMS and some light browsing of Mastodon, I can get up to 12 or 13 hours with WiFi turned off (via hardware kill switch) at best - with WiFi on I land where kop316 is.
Both of these figures are way better than they were a year ago, back then I managed to get 8 to 9 hours with WiFi off.
There’s work happening to make suspending the phone an option (that’s how the less efficient PinePhone, that’s equipped with a smaller battery manages to deliver better battery life).