While graphics applications like CorelDRAW use Fill and Outline as object properties, CAD applications usually treat fills as separate objects (shapes).
CorelCAD, supporting standard CAD techniques, also operates this way.

With the Hatch/Fill tool (in the Draw menu) you access all options for creating various fill types, including a broad range of hatch fills.
You also find multiple options for creating solid color fills.

Here's the 1st one: Selecting the "SOLID" hatch fill from the predefined hatch fill patterns in the "Hatch / Fill" tool.

The advantage of using that hatch pattern is that you can control the color of the fill in the object properties, including the option to leave color definition to the Layer (by selecting "ByLayer" color for the fill object).

2nd option, especially if you want to create more advanced color fills like gradients, is the "Fill" Type as option in the Hatch / Fill dialog.
With the "One color" option you can create gradients from the selected color to darker (black) or lighter (white) color with the corresponding slider. Specify the gradient style and angle to create the gradient fill.

With the "Two Colors" fill you can specify a 2nd color for the gradient, in case it's not black or white or a darker/ brighter tone of the 1st color that you want to create your fill with.

And finally, you can edit the properties of a color fill in the Object Properties palette with the object selected.

...leading back to the 1st option (creating a solid fill with one single color): Of course you can also use the Pattern properties to define a single color fill (instead of using the SOLID hatch pattern) - simply select the same color for both color entries in the Properties palette.