How to make a proportional grid in unity?

Question

Unity

So far, I have just started to understand Unity and the question arose of creating a grid of the playing field (such as a farm).
The question is how to make a grid correctly, the point is that the grid occupies the entire screen and can be moved, at the same time, when you click on the cell, there is an action, for example, a menu drops out?
At the same time, the question is how the actions on the cells should be remembered further? Will it be further stored on the phone or should the data be stored somewhere on the server for this?