Got my iPhone 13 Pro on 14th of January, 2022.
CoconutBattery says is at 97% battery life. I use the 20-80% rule, never charge it overnight, never charged it with fast charging. Always with a 5W Apple brick from my previous iPhones. I've only charged it to 100% when I used it at full power during the day (usually during vacations, on Maps & navigation stuff).
But, and this is a big but! Remember that the software and the way you use your device is more at fault than the hardware here.
- I don't own social apps (like Facebook, TikTok, Instagram, etc.). So I don't spend time on my phone for entertainment. Resulting in less screen time, less battery stress overtime. From my wife iPhone, I find the Facebook app to be a battery killer, literally.
- I use my phone only for phone calls, video calls, messages (iMessage or Signal), photos & videos, calendar, reminders, notes & fitness (reviewing Health & Fitness data). Btw, with iPadOS 17, I can review my Health data from the iPad also, so I'll offload that to the iPad more, and not use the iPhone if not necessary.
- I have a rule: always offload usage to a bigger battery device if available. So, iPad, not iPhone. Macbook, not iPad. iMac, not Macbook. Usually, I use my iPhone when I'm outside. At home, I have the iPad around. And while at office, I use the Macbook or iMac. So this drastically reduce the iPhone usage and the battery stress overtime.
And you have to realize that even on a vanilla iOS installation, the software already does a lot in the background. Think of Photos app, the Memories process, if you have a huge photo library that needs to be scanned. Now, it searches for duplicates, all the machine learning alghoritms applied on top to categories & detect individuals on each photo. And this is only one stock app. Not to mention Health and Fitness and all the data crunching done in the background to display statistics, highlights and recommendations.
Notifications are also a big thing. I have notifications turned on only for the phone & messages apps.
Overall, the software grows in capabilites, the batteries in these devices remain the same. Software will win, every time.