It's basically always been the same on all Android devices. "About" in Settings, click on "Version" or "Build" many times. (Sometimes one click per Android generation, sometimes a countdown is shown on screen).
"Developer Options Enabled" or some kind of easter egg graphic will inform you of success. Additional clickings or combinations can then reveal other hidden easter eggs (photo albums, mini-games, etc) - the big OEMs like Samsung always put something undocumented in their ROM to "encode" it against piracy.
Developer Options itself is usually a tick box or submenu somewhere in Settings.
