How did Apple fit the record iPhone 11 Pro Max battery? The thicc and 3D thin

Last week, the Chinese regulatory agency revealed the actual battery capacities of the new iPhone 11, Pro and Max models, and we then dug out a legal document from Apple itself confirming those to be true.
Given that the improved display and chipset processes can realistically only amount for a small percentage of that bump, had we stayed on the same 3179 mAh capacity, there had to be a larger battery in there somewhere.
Just as inferred last week, the Pro Max has the largest battery capacity in an iPhone ever, at 3969 mAh. That’s entering flagship Android territory already and explains the hearty battery life increase.
How did Apple did it? Well, it made the Pro Max slightly thicker than the XS Max, and removed the 3D Touch layer from the display package, allowing it to fit a battery pack that is thicker and larger than the one it has in the Pro Max predecessor.