I'll be completely honest with you, I never really paid that close attention to SOT or battery stats, so I can't really give you numbers. Sorry about that. The best I can give you is anecdotal, but every day I take my phone off the charger around 7:30 AM give or take ~30 mins, and put it on the charger around 10-10:30 PM. With 14.4.2, I'd hit bedtime with somewhere between 35-45% battery left. Obviously some days more and some days less depending on usage for the day, but the overwhelming majority of the days were in that range at bedtime, and most days on the higher end of that.
I installed 14.5 on Tuesday (day after release), and every day since I have had to plug my phone in during the day. Yesterday, I was at 30% around 6 PM and had to plug in to make it the rest of the evening, and tonight, I was out and not near a plug when I hit the Low Battery Mode Prompt (20%) at about 7:45.
Of course, this is all YMMV, but in my experience 14.4.2 was great. In your position, I would definitely jump on 14.4.2 before your opportunity disappears, since iOS 12 is basically ancient in phone age haha!