How to autohide top and bottom panels in RHEL 7 while application is running
I don’t think GNOME 3 or GNOME 3 classic has this function available or there any plugins that supports so.
If you need this function that the panel can hide automatically, you may consider another desktop environment, such as MATE, that supports so.
This may not solve your problem. But it’s just an alternative way to support the need.