In the settings dialogue, one can set the grid dimensions under dimensions, next, one can select to print the grid in the print dialogue. The one has a scale reference no matter the physical size of the print.
The scale is set by the track library - the physical size of the baseboard is what it is.
Here is a 12" grid layout, view option with show size and area turned on, printed as a Landscape 11" x 8.5" - it is O scale track-
What are you missing?