Is it possible to set up a flexible template so writers can pick and choose different design elements, such as pulling in call-out quotes, placing boxes for factoids or moving from two column to single column page format for a case study? We’d like a workable template with a bit more flexibility than just writing in “galleys.” Just not sure if InDesign has this capability.
You can create a Library (File>New Library) and store elements like Call outs, quotes, boxes, factoids in there for them to use over and over.
And you can create different Master Pages for 1 and 2 page column layouts.
So they would just have to Drag the 2 column layout to the current page they're on in the Pages Panel.
Make sure to create the 1 column and 2 column frames on the appropriate master pages and demonstrate how to use these properly.
It's a small learning curve for them.
Or, use Snippets.