There are features in style that support the use of exact measurements (dimensions) and those elements can be externalized so that they can be modified outside of style. Offset from plane and ratio/actual length along a curve are 2 examples of dimensions available to style features.
Create construction geometry using core Creo features and then attach the style features to the previously created construction geometry. Style curves can be snapped to other geometry (curves, points, planes etc.).
A simple 2D example to control planar curves would be to create a sketched rectangle representing a bounding box, you can then control the extents of a style curve by attaching it to the rectangle. The example below shows style curves and surfaces bounded by the red rectangle.
