It’s actually the other way around.
Porsche is a Volkswagen but a Volkswagen isn’t necessarily a Porsche.
VW bought Porsche
VW bought Porsche
However it was more complicated than that. Porche owned 50+% of Volkswagen at the time of Volkswagen buying them. Porche got over extended and leveraged buying Volkswagen . The management family is closely connected since the start and at the time in early 2010s 20% government ownership rule was just getting stuck down by European courts .