You can’t stop anyone from eventually accessing the internet, games and everything that comes with the world these days. They will find a way regardless of what you do. Age appropriate preparedness is far better than trying to protect them from it.
Parents should know their kids better than anyone and if they are capable of dealing with the content that is out there. If you’re not creating an environment in which your child feels comfortable talking to you - then you need to change your parenting techniques.
If your children can’t tell the difference between fantasy and reality or don’t know how to deal with people telling them to kill themselves, I would seek professional help.