UPDATE 27/6/23: After several days of confusion and conflicting statements, Bethesda has confirmed to Eurogamer the details in its freshly resurfaced Starfield pre-order bonus page were recently updated to provide clarification on the inclusion of a disc in certain versions of the game's physical release - and that the information now featured on the page is correct.
As such, its final word on the matter appears to be that, as below, Starfield's physical Standard Edition for Xbox will contain a disc, but that the physical Standard Edition for PC will not, instead including a digital download code for the game. Meanwhile, all versions of the physical Constellation Edition will only include a digital download code.
Starfield launches for PC and Xbox Series X/S on 6th September.