The hotly awaited GP Curve Edit Mode has just landed in Master! The brainchild of Falk David during his GSoC 2020 stint, and thanks to his unrelenting work and commitment even after GSoC had ended, this major feature update promises to take the Grease Pencil toolset and workflow to new heights.
— Daniel Martínez Lara (@_pepeland_) November 13, 2020
This feature comes in the shape of a sub-mode to the edit mode, accessed either by pressing the U key or toggling the bezier button at the top bar. It then allows for the transformation of GP strokes using Bezier Curves, as demonstrated in the video provided by Falk David below:
You can download the latest Blender 2.92 experimental build to try it out from the link below!