In my experience, yes. A Big Mac is a Big Mac pretty much everywhere. The non-US stores do often have some menu items that are targeted to local tastes, that you would not see in a mainland US store.

The McDonalds in Rome near Termini had an amazing desert bar!

I wonder if the international franchises have more freedom to vary the menu? I'd guess the standard signature items like the Big Mac and fries are pretty much mandatory though.