You most often create variants of topic, hyperlink, and file objects.
Create your primary topic object and add this to your book. Create a variant of the topic and update the content text where needed.
Filter or publish your book using the selected variant criteria to display the variant topic.
Create your hyperlink object and use it in the topic. When the target topic has variants and you publish using the selected criteria, the hyperlink points to the variant of the target.
File objects work in a similar way to hyperlink objects. The only difference is that the image in the file object is updated for each variant.
Create your primary file object and use it in the standard or primary topic object. Whenever you need a variation of the image, create a variant of the file object. Open the file object and update the image. You do not need to add the variant file object to any variant topics within the Author-it library.
When filtering or publishing the book using the selected variant criteria, Author will swap the relevant topic objects and file objects.