No. It's just the settings.
When a content creator uploads a video, you have three options...
No, it's not made for kids (default)
Yes, it's made for kids.
Age restriction (advanced) Yes, restrict my videos to viewers over 18, or No, don't restrict my video to viewers over 18 only (default along with first option)
First option along with "No, don't restrict my video to viewers over 18 only" under Age restriction (advanced) is set by default when you upload a video. These two settings are for mature audience. Videos that do not provide nudity at all, but allow gore and other things that are suitable for mature audience in terms of their policy.
Second option "Yes. it's made for kids" is basically videos uploaded that is made for kids. Content creators are prohibited from uploading any mature content under this setting. Now, it's up to the parents to properly set up their childrens YT account to only view content made for kids. And that means they will only view what is made for kids.
Third setting that is Age restriction (advanced) along with "Yes, restrict my video to viewers over 18" is simply for those who are 18+ because the type of content under this settings could have nudity for educational purposes. This setting is to prohibit those who are considered the age of maturity but are not 18+ to not be able to view these videos.