How to control initial ground Grid

We really like the initial grid under a geometry in the viewport. According to my observation, the grid is set during the first setup. Our app is a kind of open configuration and users could put various 3D objects with different sizes and sometimes the grid is small or large.

The question is we can control the parameters of the grid after the initial setup?
Could we control the number of cells or even size?

Or is it better to create a custom grid via lines directly in GH? I am afraid of a performance issue in case there is a lot of lines.

At the moment the grid is automatically generated depending on the model scale and there is no way to control its scale. I think the approach of creating one in Grasshopper would be better at the moment, although I understand your concern about performance. However, lines are very light objects and I think it should work, let me know if you end up giving it a try.