Watch out: The camera bump of the Xs and Xs Max has grown by a fraction of a millimetre compared to the iPhone X. Various online reviewers have already noticed this and if you put a new official Apple leather case for the Xs on the X, you will see a small gap. Of course, this means that the camera opening of iPhone X cases is too small by a fraction of a millimetre.
However, testers have pointed out that with a little "force" or will, you can get the camera into the hole. So I think it's best to just wait for the release to be on the safe side. It's very likely that it will fit.
The rest of the dimensions of the X and Xs are identical. So it should work.
However, it gets a bit tricky with third-party cases that also enclose the bottom of the iPhone, because the arrangement of the holes on the bottom is different on the left side. You have to look individually depending on the case design.
