In the shape drop-down menu, select a free curve in a straight line.

Hold down the left mouse button and drag, you can draw any line where you need to mark.

When the drawn line is selected, there is a drawing tool menu on it. Click "Shape Outline" on the right to set the color of the line. For example, if you choose red, you can see that the marker line on the left side turns red.

The red dimension line has been set successfully.

If the marked figure is a closed figure, when selecting a figure, you can not only set the line color, but also cover the drawn closed area by selecting a color through the "Shape Fill" function on the right. On the other hand, if the drawn closed figure does not need to be covered, just select "No Fill Color" under the shape fill.