The zoomed image looks normal to me (for small-sensor digital cameras that is).
In fact I would say that pic looks better than most. I’m used to seeing a lot more artifacts at that zoom level in digital camera images.
I'd agree that
the artefacts in those images are typical of a small sensor in indoor light.However in better lit scenes outdoors you'll see much lower levels of artefacts. A few years ago on these small sensors you'd have seen far far more artefacts,
things have improved a lot.
Apple made a point during the iPhone X introduction to mention that the X telephoto lens has a significantly larger aperture than the other dual lens iPhone models.
I have not looked for reviews of that aspect specifically but I would expect the X camera takes better 2x zoom photos in moderate lighting.