But if you are born a woman you don’t need an adjective for confirmation, it is what you are. There are so many appropriate adjectives that women can use to describe themselves, clever, funny, black, mixed race, white, old, young, adult, ,menopausal, fat, skinny, working, pregnant, British, French etc etc etc, all of which add to your knowledge of that woman, your understanding of her.
so cis as an adjective is unnecessary, she is a woman, that’s a given, we all understand that, it’s the other parts of her life , history and heritage that make her a vibrant adult human female being.
and incidentally using the adjective trans in the context trans woman is equally ridiculous, you might as well talk about a feline dog, or a feathered horse, the adjectives have no meaning or relevance to the noun.
if people want to invent a new word and call themselves transwomen then let them, that is one for the language police to figure out, but don’t start adding adjectives to the word my sex uses to describe ourselves and assuming that that makes you one of us.