Well, here's thing: 10 inches is 10 inches. The magnification (10 inches) is always the same, no matter the format. How much of the image starts "looking" wide happens to be the question.
The biggest difference between a 10" for 11x14 and a 10" for 5x7 is the image circle. This is the amount of film that is reasonably covered by the lens. The 10" 5x7 on the 11x14 might only produce a circle, and not get anywhere near the corners. I have a 360mm telephoto for my 4x5, which also covers 5x7. The lens produces a circle of light on an 8x10. However, the 10" for the 11x14 would look absolutely the same on the 5x7, it's just that you'd be seeing less of the scene on the 5x7.
I have a 75mm lens for my 4x5. If I use 4x5 film with the lens, it looks wide. However, if I use a 645 back on the camera, then the cropped image will look "normal."
So to reiterate, let's say you have a 5x7 and an 11x14 beside each other, and they use the same lensboard. The 5x7 will only show half of the scene that the 11x14 shows. Everything will look the same size. The perspective will be different, because the 11x14 will be showing a much larger picture area, and will "look" wide.