the best way to protect my child online

Kids these days grow up with technology. In a way, social media is an extension of their childhood. Because of this, it's important to talk to your kids about the potential dangers of social media. Set up filters for all devices: phones, tablets, laptops—whatever you have at home! These filters will block out anything that isn't age-appropriate for your child (which can be determined by age or maturity level), so there won't be any surprises when it comes to what they're seeing online. I also think it would be useful for you to read https://chekkee.com/14-tips-for-keeping-kids-safe-online/

It's important that they understand that they are not invulnerable, and that there are people out there who want to hurt them. It's also important for them to know that the internet is not always a safe place, and that they need to be aware of that.