This. For instance, my kids know about puberty and that someday they will get their period, and what the biological purpose of their period is. They've been told how babies are made, but not the actual sex conversation.
I answer their questions but try not to get ahead of their questions or their age.
Eta: we've talked about their bodies neing theirs and how no one should touch them and they should never ever feel like they have to do something thar makes them uncomfortable from very early on.
I've also talked about drinking and drugs and peer pressure, in an age appropriate way. I've been talking to my daughter about peer pressure, such as, she shouldn't do what her friends are doing if she feels uncomfortable or feels its wrong, and she shouldn't ever be afraid to walk away. We've also talked about drugs, the difference between what the doctor gives you and others, and staying in school, inappropriate content on tv, being safe on the internet.
I have very open conversations with my kids. I try to shelter them to keep them 'kids', but I talk to them like they're people, about real stuff, and often.
My mom talked to me about sex when I was 8. I think I was too young and it felt traumatic. I also think she was 'too' open with me at times. I won't do that, but I talk to my kids on an appropriate 'friend' level bc I want them to feel comfortable talking to me, not afraid bc they only see me as this 'higher power'.