Designing a helicopter that can land and takeoff from a 5 x 5 meter pad at an altitude of 23000 feet would pose no insurmountable engineering challenges. The design difficulty depends greatly on the desired performance (e.g. useful load, speed, endurance, environmental envelope) at that altitude; but that is true at any altitude. Helicopters cannot, at current levels of technology, be designed for excellent performance at all altitudes.
This is more an economic than an engineering problem. There is little demand to operate at those altitudes. Individual unit price for a helicopter meeting the altitude performance you have asked about would be greater than most governments would be willing to pay.
There is not a manufacturer in the world that has not been approached by the Indian government for a helicopter that can operate at high mission altitudes. Unfortunately the Indian government and/or business sector have not proposed a single, well defined performance criterion for the high altitude mission; nor has it demonstrated a willingness to pay for a helicopter designed for very high altitude performance.