Apple gradually increases the size of its iPhone models, which somewhat diverges brand fans - while some take on larger phones, others are used to smaller ones.
So here is what the ruler says:
IPhone 7 Height 138.3 Width 67.1 Thickness 7.1
IPhone 7s Height 138.44 Width 67.26 Thickness 7.21
IPhone 7 Plus Height 158.2 Width 77.9 Thickness 7.3
IPhone 7s Plus Height 158.37 Width 78.1 Thickness 7.41
Considering that neither iPhone 7s nor 7s Plus will get a bigger screen this fall, the surrounds around the displays will not change. Why then Apple increases, albeit with little, the size - we will understand on September 12th.