Hey StarGazerX, you’re looking for a message monitoring feature, and most solid parental control apps have this built-in. I’ve been using Parentaler and it does exactly what you need. It lets you read the full content of all sent, received, and even deleted text messages, so you get the complete context.
Pro tip: Once you set it up, create a custom keyword list for words you’re worried about (like “drugs” or “bullying”). The app will send you an immediate alert if those words appear in a message, which is a huge help for staying proactive.