Sure. In a Harry Potter fanfiction, there could be a call to action where the students of Hogwarts form a resistance against a new dark wizard who has infiltrated the Ministry of Magic. They call on all magical beings to unite and fight against this new threat, which is a call to action within the fan - created story.
One example could be a Star Wars fanfiction. Suppose in this fanfic, the rebels discover a new and even more powerful Empire - like regime is being built in a far - flung part of the galaxy. The main characters issue a call to action, rallying all the different species and planets that have been oppressed by the previous Empire to join together and stop this new threat before it grows too powerful. This shows how the concept of a call to action can be used in a fanfiction based on a well - known universe.