Vary Unity Game Landscape Height according to Google Sheets Values

I have a Unity Project that I have been working on, the project is already connected to my Google Spreadsheet so when you import my Unity Package it will already be connected. Currently the project reads an Object list and places objects on a flat XY square grid (26X26). The Project needs a variable that cancontrol the XY of the Square grid so I can make my game landscape bigger. So there should be a simple variable that setx X and sets Y. So if set X as 200 and Y as 100 it plots a 200 X 100 Square grid. The project wil then need another variable that sets Z (the maximum height of the landscape). If the square A1 on the grid is 1m x 1m and the Z value 26 then the altitude (height) of the A1 is 26m. A2's Z value might be 25 and A3 might be 24. The Z values will all be generated in the Google Sheet. your job will be to make a landscape plane that reads the values of the Z values and plots them to the relevant XY co-ordinates. It will then need a smoothing effect to transition between the values. The Unity game I already have then places an object list ontop of this XY Grid (26X26) please make sure that the objects are placing on top of the landscape and are not still at Z is level 0.