Does an iPhone 7 fit an iPhone 8 otterbox case?

The case size is the same, however the location of the screen side camera is different. As long as the Otter Box you are considering is completely clear across the top of the face, above the screen, it will not interfere with the operation of that camera.

Yes, they are the same outer design.

So any iPhone SE2/iPhone 8/iPhone 7 Cases fits all.

For otterbox: Check out this page:

https://www.otterbox.com/en-us/iphone-8

On all the iPhone 8 cases iPhone 7 is also listed as compatible.