I’m worried about my kid’s online safety and want to keep an eye on their conversations, specifically on Messenger, without them knowing - is there a way to monitor their activity without having to install some kind of tracking software on their device?
Re: Is tracking messenger possible without installing an app?
Hey sharon88, short answer: no, not really - anything that actually reads Messenger conversations needs either an app installed on the device or account-level access (like knowing their Facebook login).
The good news is if it’s your kid’s phone, you don’t need to be sneaky about it - just grab the phone, check Screen Time (iOS) or Digital Wellbeing (Android), or log into their Facebook account directly since you probably set it up anyway. 
Honestly the most reliable combo I’ve seen parents use is shared account access + an open conversation with your kid about why you’re checking - way less drama than third-party apps and actually works long-term.