This seems to have gone missing in the latest version, has it been removed or re-located ?
This looks like what you were hunting for!
You could try the following:
Goto Tools - Options - LibreOffice - Advanced and select Enable experimental features checkbox.
You’ll need to restart LibreOffice.
After this, select View → User Interface and try one of the newly enabled views like “tabbed” or “contextual groups”.
It appears that the “Gear” option was not present in version 6.05 but is available in the newest version 6.1.2.1