Working with CorelDRAW or graphics applications in general and CorelCAD (or CAD applications in general) you may notice there's a slightly different paradigm when it comes to Layer management and how Layers are used to structure a drawing.

One aspect that is handled differently in graphics and CAD applications is line color.

In CorelDRAW or Corel DESIGNER, you typically assign outline and fill colors to the individual objects. There is an option to assign a specific color to a layer, but that's primarily for monitoring your layout in "Wireframe" display mode. The layer color in CorelDRAW does not impact the output (color) of the objects on that layer.

In CAD tools like CorelCAD, colors are typically assigned to layers and all objects are assigned the color “ByLayer” so that they display in the color that has been defined for the current layer they’re on.
The line color in a CAD drawing also becomes important when outputting (i.e. printing) the CAD drawing as you can assign line weights to colors so that all red lines are output as 0.18mm (black) lines for example.

This means that repurposing graphics files for CAD may require some rework to move from the graphics to the CAD world of layer and color concepts.

When importing *.cdr or *.des to CorelCAD, you will need to manually tweak the imported objects with the following steps in order to use the CAD concept of color definition by layer with the imported file:
After finishing the import,

1. Go to Model space (Model tab below the main drawing window) and select all objects (Ctrl+A)
2. Go to the Properties docker (palette) (if not active, you can open it by Ctrl+1)
   
   Note that most of the properties listed will show a “*VARIES*” entry which means there are various values used for that property with the selected objects
   Navigate to the “Line Color” field and select “ByLayer” from the dropdown list. This will change the color of all objects to using the color defined for their layer (probably all objects will appear white after that which means they are black on white paper).
   
3. Now go to the Layers Manager dialog (Format menu > Layer…)

   and apply the intended Line Color to the layers as you need it:
   

…following that all objects will appear in the line color of the Layer they have been created on after that step.
Moving an object to a different layer in CorelCAD will then result in the object being displayed in the (different) color of that target layer.

When exporting to CorelDRAW or Corel DESIGNER again later on, the objects will be converted to using the Layer color definition as their own object line color so that you don't need to do anything to repurpose CAD drawings for creative graphics tasks.