You can adjust thickness of a point on curve.  Use this feature to create 3D signatures or line sketch in higher quality.

1. Create a Ink or Stroke curve and enter edit mode.

2. Grab a control point and swipe Touchpad* left or right to adjust the size.

*Move Thumbstick to left/right for Oculus/Valve

In Gravity Sketch you can also adjust Normals of a curve to twist it more dynamically. Toggle mode by swiping Touchpad* on your drawing hand.

Point mode: You can grab, move, copy, and delete individual control points.

Normals mode: Swipe Touchpad* on a Ink or Stroke curve to access. Normal editing allows you to edit the twist of strokes along their path. 

*Move Thumbstick to left/right for Oculus/Valve