Are the iPhone 11 and iPhone XS Max the Same Size?

No, the iPhone 11 and iPhone XS Max are not the same size, although they are similar. The iPhone XS Max is a bit bigger with a screen size of 6.46 inches, while the iPhone 11 has a screen size of 6.1 inches. 

iPhone 11: 150.9 x 75.7 x 8.3 mm (5.94 x 2.98 x 0.33 in)

iPhone XS Max: 157.5 x 77.4 x 7.7 mm (6.20 x 3.05 x 0.30 in)