I told my 5yo son about sex, as in penis in vagina, and how a baby is made. I won't cover sex for pleasure until maybe like 10-12.
It depends how old your daughter is, in my opinion. Kids are exposed to all kinds of talk when transferring to secondary school
I was 14 when I had the talk with my Mother. My son 11, he asks questions, I answer truthfully. When I fell pregnant he asked about sex and babies. It depends on the child, my son known about periods since he was very little. Called pads mummy’s nappies.