Child communication limits

My son has an iPhone that we have family safety set up on. We have it set up so that he can’t text people he doesn’t have set up as a contact in his phone. It’s a nice feature so he doesn’t fall for spam texts, etc. The only thing is that it’s kind of a pain when he exchanges phone numbers with someone new. The message comes through with their number listed, but even with the Screen Time passcode I can’t view the message without adding them as a contact first. He doesn’t always know which numbers belong to people he knows and what’s spam/junk. I was wondering if there’s a way I can preview the message before adding it to his phone as a contact.