Bug 276378 says it was implemented in 2011 but I can't find the option to specify the server name (CN) of the 802.1X server certificate. Network Manager, nm-connection-editor, Windows, MaxOS and Android >7 all support this feature, but plasma-nm and the gnome front end do not. Without this verification there is (almost) no security for 802.1X.
I think this has been added to master recently. See https://cgit.kde.org/plasma-nm.git/commit/?id=97cd51d3099402129e2ec411c918e8b51f766f42.