They can try, but it takes more than a few words of "be careful" for children to actually understand and learn and practice the right kinds of behaviours to be protected.
That's one of the main issues that I see. For one, it's not done with good words. Nobody ever didn't get into a car crash because mom said "drive carefully". The first step would be to create such a close relationship with my child that she trusts me with her feelings, because a lot of times it starts with "feeling weird" but being manipulated into not giving into that instinct. That goes further into trusting the gut, the instinct - when something is weird, better have it checked.
But to feel weird, there needs to be a level of experience, and that has to come from somewhere - not from direct experience with the action, but maybe through education. Having the theoretical knowledge, building from small things that feel weird. Again, if the relationship is close enough, she will tell me when there was a violation of her personal space, even if that was just another child getting too close, or saying things that don't seem right. It doesn't have to contain sexual ambiguity or something like that, but just be a anchor to talk about personal space, and based on that validating the feeling of "weird".
That's more or less how far I have come with that, until now. If you have more thoughts or ideas or links to tips about that, I'd be grateful.