How to check if the user is authenticated in another authorized app

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Hi Everyone,
I have a quick question
In Auth0 tenant, we have several apps and one has integration with another.
If I am logged in to App1 and try to access App2, how can I check if the user is authenticated?
I believe once a user is authenticated Auth0 creates a session for the authenticated user
I am trying to use this but not working:
HttpContext.GetOwinContext().Authentication.AuthenticateAsync(“ExternalCookie”);

Note: I don’t want to perform a single sign-on login again.