* iPhone 5: 4.87 x 2.31 x 0.30
Volume: 3.37491
* iPhone 12/13 Mini: 5.18 x 2.53 x 0.29 Volume: 3.8
* iPhone 6: 5.44 x 2.64 x 0.27 Volume: 3.877632
* iPhone 8: 5.45 x 2.65 x 0.29I would argue that 9% is far from marginal.
The increase from a 12 mini to an iPhone 6 is very minor; the increase from a 6 to 8 is marginal.
From a 5 to a 6 or 12/13 mini is substantial.