One method: 

 1. First, activate Double polyline by clicking the outlined "D" icon if you haven't already.
 2. Select all points with Shift-A
 3. Hold the "O" (offset) key and click-drag in the viewer.

There are other ways to control double polylines. More information can be found in the DaVinci Resolve user manual.  As of version 16.2, the relevant pages start at 1298.

Key bindings in Fusion are editable.