Environment Designer in Unreal Engine

I need an Environment Designer to design a 6-7 square kilometre map for an open world mobile game based on the real map of the city of Mumbai, India. Basal Structure and landmark buildings, props, and other 3D Models will be provided, the requirement is that the Map/Environment should be detailed, realistic, and optimized for a Mobile game. This is also a long term project where if the company is happy with the work, more contracts could be given in the future.

Note that all of the Environment building must be done in Unreal Engine.