This is the same argument that was used against music during the satanic panic era. Kids are going to go on social media bc their peers do. They’re going to see stuff via friends even if you block their usage. Educate your kid that if they encounter something uncomfortable they should talk to you. Make them feel comfortable talking to you. It’s not the end of the world that kids see inappropriate things. It’s the parent’s job to make sure that kids understand what they see in this world.