Viewport Shading / Studio Lighting custom preset?

Is it possible to create custom Studio Lighting presets for Flat Viewport Shading?

Or would it be better to try and set this up as a look in an Eevee render?

I like the flat look of the Viewport sometimes and would like to use something similar for diagrams.

As I understand it the Viewport uses Workbench and whatever is set up there, is that right?

I found this thread with a similar question, one answer being this set of Studo Lighting presets created by @AFWS, is this the only way?

um, it looks like you can.

I found this page in the Blender 2.81 manual that mentions an ‘Editor’ that I totally missed in the Blender Preferences Lights section.

Clicking on Editor then Edit Studio Light allows you to select and edit up to four lights then save the configuration.