Here are some renderings using iclone toon shader. I used photofiltre to stylize the 2D backdrops.

Thank you for showing these.  Can you tell me if they have fixed the outline scaling issue which started about 2 1/2 years ago?

I refer to this request:  https://www.reallusion.com/FeedBackTracker/Issue/TOON-Shader-outline-is-broken

If you look at my examples you can see the problem.  Have you tried rendering at various resolutions to see if the outline is working now?

Please let me know -- I have been stuck at version 7.2 waiting for this to be fixed.

I don't know if this helps you or not. The blonde or light brown hair seems to show outline of head.
I just darkened the hair. 
The first picture is a screenshot showing the settings ( I also added DH Full Body Epic from Atmosphere).
You can can adjust the strength of the atmosphere settings 0-100. 
The second picture is a rendering (1920 x 1080) of the avatar in the screenshot.
The third photo is a screenshot with Toon shader template and no light.
The fourth photo shows a screenshot of created directional light,
The 5th photo is a rendering of the forth photo.
The 6th photo shows the Atmosphere I used. It was the best one that showed the avatar in a brighter light.
I did not test all of the atmosphere. If you use atmosphere, it turns off toon shader.
You just go to toonshader and click box.
I don't know if this helps you or not. I am no expert.

Thank you for taking the time to post this.  Unfortunately it doesn't answer my question.

If you have time I would appreciate it if you could make one more test for me:

Render a single frame toon-shaded image with a black outline of 1 pixel at 1000 x 1000, then render exactly the same frame with a black outline of 1 pixel at 3000x3000.  If the outline remains constant (i.e. 1 pixel) then there will be a difference in the two frames -- the larger image will appear to have a smaller line.  If the outline becomes thicker in the larger rendering, then they haven't fixed the issue.

Thank you for your time and patience. :-)

Here are the renders at default settings of edge width 1 and edge intensity 80.
The first photo is 1000 x 1000. the second photo is 2000 x 2000.
In another post, I posted a photo I rendered in 3840 x 2160 and reallusion downsized the photo a lot.
So that is why I did not try 3000 x 3000.

Thank you for taking the time to do this. It is really appreciated.

In renders prior to 7.3 the line width of 1 was a single pixel.  Whether you rendered an image of 100x100 or 1000x1000 the outline width was always a single pixel.  This meant that you had more control over outline width -- if you wanted a thinner outline you could render a larger scale image and the outline wouldn't get bigger.  Since 7.3 the outline is scaled with the image, and it looks like crap.  The outlines on your images are too thick, and scaling back the intensity doesn't help.

It shows that Reallusion still hasn't addressed the problem AFTER TWO AND A HALF YEARS!

Thanks again for your time and patience -- as you can probably tell, my patience is all worn out.

Sorry it has taken so long to reply properly, but these are some rendering from the toon shader in 7.2.  The Avatars are hand textured (very simply), but the most noteworthy feature is the LINE WIDTH.  It is one pixel even at a resolution of 1280.  This makes the objects "cleaner", not just in the outline, but in the interior details.  The setting is 1 unit at 80%.

In other words, these images are no longer possible with Iclone.