They can probably get around that by carving out the Mall, the Capitol, and the White House and leaving that under the control of Congress and making everything else a state.
The article defines the district as "...not exceeding ten Miles square..., but doesn't say if Congress can make the area smaller.
Again, this one needs to be adjudicated for clarity before any vote can be had.
Congress cannot carve out a state from an existing one without the consent of those states — DC being part of VA and MD would require their assent (both Dim run)
— oh, unless its during an insurrection. Aha!