Not exactly - you can then push all branches and they will be the same but then if the source repo changes you need to manually push for you. True sync would do this for you, along with ideally issues/wiki/etc.
Gitlab definitely does this automatically for you if you mirror the repository. Or am I misunderstanding how this feature works?
This made me think the gp was referring to Gitlab (pull sync) but you're right, they may have meant Github (push sync).