The city of Kattegat from the Vikings TV show isn’t an actual historical city, so - no. Instead, the real Kattegat is an area of the sea between Norway, Denmark, and Sweden. Nevertheless, it is believed that Lagertha was a queen in Norway for a while and ruled both at Ragnar Lothbrok’s side and on her own after she assassinated her husband (whether that husband was Ragnar himself or her second husband isn’t clear).