I believe the setting you are looking for is zoomSpeed. https://wiki.dendron.so/notes/3i4ABJutl7NGeXRHTnUEC/#zoomspeed
You can update this in your dendron.yml by running Dendron: Configure (yaml) and update the workspace config:
workspace:
graph:
zoomSpeed: 1
It has a default value of 1. This configuration updates the wheel sensitivity of cytoscape(the library we use to build a graph). More info here:
https://js.cytoscape.org/#init-opts/wheelSensitivity