It is not possible to have any insight which Offerings make use of any particular Fulfillment Plans.
The Idea is:
From an admin’s perspective it would be great to have some kind of overview of which Offerings use a particular Fulfillment Plan. By having such an insight you are able to determine the impact of planned changes to a Fulfillment Plan.
This also saves time to browse through many Offerings to check if these use the to be changed Fulfillment Plan.