This was one of the things I loved about the iPhone X leather case. It raised the thickness of the device flush with the camera module so that the phone would lie flat on a surface.The only reasons I get a case for my iPhone is to avoid wobbling, but it looks like that won't be avoidable even with a case now - very disappointed if that is true.
The 12 models have cases with a plastic "ring" around the camera module area, which creates just enough of a difference between the case surface and the plastic that the phone will wobble or rock a tiny bit while lying on a flat surface. I really hope they don't do that again with the cases this year.