While it’s true that there are certain things like the Enchirito that are officially off the menu, for the most part Taco Bell doesn’t have a secret menu. Basically, if they still have the ingredients they can make it but special order items will cost extra. Not every restaurant has chili, and you can’t go to a Taco bell and order an “Incredible Hulk” and expect the employees to know what the hell you are talking about. Quite like the Starbucks secret menu that doesn’t exist.
Things some Taco Bells still serve:
Enchirito (still a register button for it)
Cheesy Gordita Crunch (which is now in a combo in places)
Cheesy Fiesta Potatoes (still a register button for it)
Baja and Nacho Cheese style Chalupas
And funnily enough, the green sauce was never mentioned even though it isn’t on the menu anywhere.