It’s not frequency that does anything there’s no such thing as a racial frequency as everyone’s frequency is capable of changing based on many factors. Becoming a demon doesn’t need “ascension” nor does it need a change in frequency.
The goetia strengths and weaknesses vary and a person can surpass the goetia if they wanted. The goetia are nothing but a rank among infernal demons not an end all be all of to anything.
Becoming a demon after death is possible and becoming a demon while currently reincarnated is also possible through the request of a Deity such as Nyx, Lucifer, and such. However, some demons along with the goetia can alter the soul into one as well. However, I’d suggest a deity before a goetia or any demon as the method seems smoother with the former than the latter as the latter it’s more of a “corrupting” the soul in a way it’s basically forced changed.