I have integrated a Print to Scale function for scenes (when in Parallel projection).
So, you can assign a scale to each scene individually (you may not need a layport, but if you have one, you can center the 2D view in addition).
In the following model, I have 2 scenes of a cube of 1m size. I have assigned a scale of 1/10 for the first scene and 1/20 for the second scene. Here is the output in Layout.
HOWEVER, I noticed, at least on my own printers that the physical printout can be slightly smaller, because the printer would scale down a liitle bit and leave margins around the print area.
For instance, with my Laser printer Brother MFC-L3750, the print area is smaller by 1 cm in height and width (this seems to a physical settings, as I did not find an option to change that). For instance, the size of the cubes is only 9.7 cm when measured on the physical paper, where it should be 10cm.
On a regular Canon Inkjet, this is fine: the printer seems to use the whole page as the print area.
Is this an issue you encounter?
If so, I can easily add a paper correction factor by printer to rectify the scale-down of the print area versus paper page.