There is a script to render a grid as a path, and you can use View>Snap to active path to have the path act as a guide. But you would also have to move the path afterwards to center it (Move tool in "Path" mode), since the script only takes an offset. The script is here.
As far as I know, there's no automatic way to centre the grid, since it would depend on the size of the grid, and the size of the canvas. I suppose one could write or find a script/extension for this, but I don't know of one. However, it's easy enough to work out the required offset using some simple arithmetic
For the sake of an example, suppose you have a ...
For those who are still wondering, here's an Isometric Grid Template I made with the grid overlaying an artwork layer.
You are free to download and use as desired.
I made a bunch of triangles laid out, then applied a thin dashed stroke at a lower opacity on a locked layer above the artwork.