How to modify the SIZE of the standard game objects?

Is it possible to modify the size of the standard game objects (e.g. plane, cube, etc.) instead of scaling them?

I need the width and length of objects to position them side by side. When I scale the objects I have to consider the scale factor and that makes positioning more difficult than necessary. So is there a possibility to get an change the size of these objects?

I think the scale in the standard game objects, is the actual size of the object.

You can't.

If your project specifically requires this, you might consider making your own versions of the primitives by building a mesh from scratch using the Mesh API. That way, you can position the vertices wherever you like so that your object is at the desired size when its scale is 1,1,1.