Calling a different action method for the same URL

Scenario is something like this:

I have a website where users can create their own stores. Upon creation, they have an option to choose a store template. Right now, whatever template you choose, when you go to a URL (lets say /home), it calls the same action method and then does a call to BLL from that action method.

Now, I want to retrieve data using ASP.NET Web API instead of directly from MVC Controllers but I want it only for 1 particular template. It still needs to have the same URL for /home as the other templates even though its retrieval is different now.

I wanted to ask if there is a way that I have a global flag that I can turn on (eg. APIEnabled) and then based on that flag, use a different action method from the same GET request.

I understand that with this flag I can just do a condition inside the action method but I feel it will make my Action methods messy.

#asp.net