The new drag-and-drop interface does not have row and column components. The replacement for those is the “group” component. However, I don’t see a way to create a custom layout from a group component. I did notice that if I add a data viewer grid to a screen, I can select previous custom layouts I created in the legacy interface. But I don’t see a way to create new custom layouts. I think you might have to use the legacy interface for that.