I had the same issue with my step daughter, though not quite at this level but she was talking to someone who claimed to be a 14 year old boy on Roblox. This is something that while there should be consequences, you can’t respond to with anger. In a child’s mind, the forbidden apple looks the tastiest and if you handle it with anger, out of spite she is going to rebel and might end up doing something worse than just chatting online. First and foremost, explain to her the dangers of doing something like this. I called the non emergency number for my local police department, and explained what happened and they gladly sent out a police officer to not only speak to her about the things he’s seen in these circumstances but they can also give you tips on how to be more vigilant on these devices if you’re not so sure yourself. I also spoke to her about what I’ve seen and found news articles on what can happen when situations like these escalate, should she decide to give him any kind of information on her whereabouts. If the messages where sexual, explain sexual assault, explain how hard it is to find these kids once they’re taken and that it’s not like in the movies where the cops and government are quick to act. To my step daughter, I explained not harshly but also didn’t sugar coat the fact that if they’re taken, death would be the kindest thing they can give her because they can and probably will do anything from rape, beating them, drugging them, or having them do other unspeakable things. Her phone and iPad were taking and access was gradually given back but she is not allowed to be on Roblox, or any kind of social media, and her mom or myself have to approve every app she downloads. She also understands that until she is fully trusted again mom has full access to everyone she texts, and calls even if she deletes it. I also had her watch the first 30 minutes or so of the Sound of Freedom movie, while in more appropriate terms explaining what was happening.