There isn't a group that specifically contains all authenticated users, but you can create a group containing all users within a tenant using a membership rule. https://learn.microsoft.com/en-us/azure/active-directory/enterprise-users/groups-dynamic-membership
There aren't any official samples for this that I'm aware of, but there is actually a C# example of querying all users in a tenant this similar thread.
Let me know if this is what you are looking for and if I understood the ask correctly. I would be happy to discuss this further.