In the novel, she is is a normal kid who does not act or dress provocatively.
It is the mentally ill narrator who misinterprets her every word and gesture to justify his predation.
I’ve been thinking this for a while and came across this article which exactly that. Projecting the current ‘over sexualized nymphet’ culture on the novel is borderline obscene not to mention false.
And worse, he MARRIES the mother to get access to the child! (at least, that is my memory from reading it 25 years ago.)