Is it possible to turn layers on and off when viewing Story Map applications?
Last Published: April 25, 2020
No, it is not possible to turn layers on and off when viewing Story Map applications. Story Maps are designed with a focus on creating a visual story through dynamic maps. Since Story Maps are mainly intended for use by a general audience and do not require the application to be configured when being viewed, the ability to directly turn layers on and off is not included.
However, most of the Story Map templates available incorporate the functionality of toggling between layers in different ways, which achieves a similar purpose as turning layers on and off. Layer toggling allows users to switch visibility of the layers to control what is displayed on the map between views.
Depending on the information that must be conveyed, the author of the Story Map can select a suitable template and determine the combination of layers to be shown as the application progresses for an improved storytelling experience. For more information, refer to the following GeoNet thread, Which ArcGIS Online applications allow users to turn layers on and off?