I discovered that low-poly models can sometimes be more effective for an illustrative render. Initially, I added subdivisions to my plant models, but this made them too smooth and CGI-like. Keeping the low-poly edges helped the toon outlines resemble sketched lines.

https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_user_guide_ac_openpbr_thinfilm_html

Thanks to @zapandersson for the recommendation.

https://forums.autodesk.com/t5/arnold-for-cinema-4d-forum/c4dtoa-4-7-7-released-with-cinema-4d-2025-support/m-p/13014048#M9663

https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_user_guide_ac_openpbr_transmission_ac_nested_dielectrics_html

“I admire its purity. A survivor, unclouded by conscience, remorse, or delusions of morality.”

https://untoldstudios.tv/projects/knuckles-making-of/

https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_user_guide_ac_surface_shaders_ac_open_pbr_html