Bob
Turbo Cad has the same capabilities as AutoCAD the problems arise when the design includes readily available materials.
For example think about 6mm x 6mm stringers in a 4ft design.
If you wanted to reduce the design to 3ft the size of the stringers would change to 4.8mm x 4.8mm.
4.8mm x 4.8mm isn't a commercially available size so the stringers on the 3ft design would have to be changed to 4mm x 4mm.
Now consider all of the other drawing dimensions that will have to be changed to suit commercially available materials.
The upshot of all this is that changing sizes isn't as simple as flipping a switch.
Paul