How can I create rectangles in another rectangle

Modelo javi.pdf (6.3 KB)
Hi, I would like to know some way to achieve what I want to do, since the only way I can think of is very long.

I want to divide a rectangle as if it were a window, to specify only the number of rectangles in x and y and the separation between them.

I suppose there must be something already created but I can not find it, thank you very much.