At least this article doesn't say anything about that. In fact, it presumes all cores have turbo (which would make sense): At the peak turbo of 4.0 GHz, or for all-cores somewhere in the middle (again, Intel won’t specify), the power will obviously be higher.

Later they do some "sleuthing" to quote them and come up with this chart which again indicates turbo across all cores: https://images.anandtech.com/doci/12607/Turbos.png