There are already children’s and YA sections in physical libraries.

As for online the Booktok stuff is trash but censoring fictional things that make people uncomfortable isn’t going to address the occurrence of domestic violence in society.

I feel like it would be more effective to supervise and have age appropriate discussions with kids, because a nebulous age rating system isn’t going to catch everything or prepare them for challenging content or situations when they get older.

And if they’re so concerned with family violence they should address the actual causes and consequences.