These weapons are intended to eliminate or greatly reduce the main strength of the US which is it’s power projection.

These won’t be used against cities but they can take out naval groups and any regional bases the US has.

If China gets to the point where they can effectively contain US power projection they would be able to operate in their region and much of the Asia Pacific without much of a challenge.

Challenging the US blue water capability and thus its power projection with symmetric means is a near fools errand.

This is why China is focusing heavily on “carrier killers” and on slow creep of artificial islands that would allow them to project their own power without matching the US in terms of naval assets not to mention naval experience.