A country's executive lays out the basic information that it wants to have, but the specific formulation that is used in the census or the specific method that is employed to obtain that information is typically left to the statistics office.
In many countries, you do have a ministerial conclusion that a particular survey or census should be conducted at a particular moment, typically because you need budgetary resources to do so. The technicalities of how it's being put in place and how questions are being formulated is typically something that is left to statisticians.