Only thing I would be worried about, what if the iPhone 11 pro Max battery life and size is a one off? Meaning iPhone's are hit or miss each year on battery life. The XS Max had mediocre battery life, nothing great. And I believe it was the 6S Plus or one of or two of the Plus phones also had good but not great battery life. I know the 11 Pro Max is off the charts outstanding battery life, but I don't think that's typical for every Max and Plus phone, to be #1 battery champ phones of the year.
The iPhone 12 is supposed to be all screen, no notch, and thinner and lighter. Makes me think I could see Apple lessening the battery life a bit lower, to make the phone they want.
I'm the type of guy, saying make the phone thicker and heavy if need be to squeeze in a large battery. If I designed the Pixel 4 XL, it would have a 4,300mAh battery, 8GB RAM, and have a 512GB option, and that really shouldn't cost a ton more, but make the phone from very good, to excellent. Heck, I'm almost of the belief to shove in 5,000mAh batteries in flagships, go all out, who would complain for true 2 day battery life?