Hi @RachelAllen ...
The "Canvas Elementary Theming" Feature Option appears to be something that can be enabled by Canvas administrators. In a paid Canvas account, Canvas admins can enable this for everyone, or they can enable it so that instructors have the option to use it (or not) on a course-by-course basis. In the Free For Teacher Canvas environment, there is no administrative functionality like there is in a paid Canvas environment. So, when you go to your own course "Settings" >> "Feature Options" tab, you don't see the "Canvas Elementary Theming" toggle switch. This is the Guide that is associated with the Elementary Theming:
I know this might not be the answer you were looking for, but I hope it helps to answer your question.
