Create placeholders in grid layout group?

I recently started using the layout groups which made working on my game 10x easier.

But I was wondering if there was a way to make the grid layout group cells in static positions? Like stop them from auto arranging to top left etc.
Or would I have do create cells equivalent to my grid size and make them placeholders for my objects?

No. You need to either create your own grid layout (not recommended, there are a lot of things to take in account), or simply place elements in every grid position, that can be empty or full.