How to create subtabs (or dropdown list under the tabs) on the Map Series Builder? Is it possible?
Thanks for your question. I'm not sure exactly what the tabs would do, but it sounds like this change is only something that could be done through customization of the application code.
You can download the source code from Github if you are interested in doing that:
Esri/map-series-storytelling-template-js · GitHub
If you are looking for a solution without coding, you can embed story maps inside story maps, so perhaps embedding a Map Series or Map Journal app inside another Map Series app might get you the experience you are after. See this blog for more information on how to do this:
Embedding a Story Map within a Story Map | ArcGIS Blog
However, be careful with this technique as you can quickly create a very complicated and confusing experience for your audience, so use it with caution.
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