Tech enthusiasts were saying that OLED displays will consume less power than LCDs as OLEDs don't have backlighting. Further, Apple has quoted "15hr video" playback for 12 Mini battery. 15hr video playback is quoted with 5g in mind also. Since, there is no 5G in India, we might get 16hr video playback or more. 5G is very power hungry. Also, 5nm chipsets are highly power efficient and well optimized.It's not about 5G bro. It's because of high-end specs and low mAh.
2340x1080-pixel resolution at 476 ppi XDR Display, 625 nits (1,200 nits HDR) brightness, HDR10 Video Playback and all other things with just 2227mAh battery.
iPhone SE was with old specs and 1821mAh but still, it's hard to pull it an entire day for an average user because of this I highly doubt about 12 mini. If the battery turned out to be good it will be a miracle and mini might become the best selling device.
In Apple smartphones, battery will not drain when the smartphone is idle.
So, Anything over 5hr of SOT will do good.