In foreign affairs, Beijing is sovereign - including anything related to the Senkaku / Diaoyu islands which are presently owned by Japan. So in this respect you are right.

For local matters, there is considerable flexibility and internal conflict. Currently, Beijing encourages citizens to find fault and report administrative issues at local levels, but will brook no dissent of its own management. In domestic administration China is less coherent than your claim.

All of the above could be equally true in a non-authoritarian form of government. I would argue that China's authoritarian politics are largely orthogonal to its degree of federation.