In Bridgerton Daphne, the eldest girl has absolutely no knowledge of what sex is, what the penis is, what it does, or how women get pregnant and have children, even once she is married.
She isnt shown to be naive- she knows women get a 'reputation' for going into a maze known for hooking up, and is seen spending time with her brothers in inappropriate venues like the boxing.
Is it accurate that she would be kept so in the dark when she has older brothers she is close with, is around animals, and has many friends of a similar age? Would there not have been gossip and whispers from women who were more adverturous than her, even if her mother didn't prepare her?
More can always be said about this, but u/mimicofmodes has tackled the question of Daphne Bridgerton's ignorance about sex in this answer.
/u/mimicofmodes answerd this here