@HughesTooling -San.
The add-in has been completed and is attached.
It works like this.
When the add-in is executed, the command "Create Plane Sketch" is added next to the "Create Sketch" command in the "DESIGN" - "SOLID" tab - "CREATE" panel.

After executing the command, you will be able to adjust the offset distance by selecting a plane, set the desired distance, and press the OK button.
After the command dialog disappears, the sketch is created based on the new offset plane and the sketch is edited.
The following are points to note.
・The command is only available in parametric mode, as there were some problems when we tested it.
・The planes that can be selected are the construction plane and the flat surface of the body.
・The size of the previewed plane is different from the "Offset Plane" command when the origin plane is selected.

・There may be some problems due to lack of testing.
This is an advertisement, but we have released an add-in that adds several commands to make the sketching process a little easier.
https://github.com/kantoku-code/Fusion360_SketchToolPlus
Most of these commands were created based on questions and requests from users in the Japanese forum. Please try them if you like.