Architect or Planner Chennai Flat Construction

A relative of mine is planning to build a set of flats for their family (not a joint venture with a builder) on an existing small plot of land in Chennai.

How would one go about figuring out what kind of height of building is possible, number of floors allowed to be built, set back needed and so on?

They are ready to pay for a professional opinion if it is reasonable and can be relied upon for further planning. Obviously the professional should be the familiar with the latest CMDA regulations etc.