Spline (2D)
- On the  tab, in the Lines
        group, click tab, in the Lines
        group, click Spline. Spline.
- Select the line properties.  Line Properties Line Properties
- Click four points, at least.
- Select Confirm.

Vertex G4Plant 2021 (27.0)
 tab, in the Lines
        group, click
 tab, in the Lines
        group, click  Spline.
Spline. Line Properties
        Line Properties