Is it possible to read someone else's texts without them knowing?

I’ve been worried about my younger brother’s online activity lately, and I’ve seen some apps claim they can do this, but I’m not sure if it’s actually possible without jailbreaking or installing something on their phone. Has anyone here successfully monitored texts remotely, or is it just a scam?

Monitoring texts usually requires the target phone to have specific apps installed, often with you needing physical access. Claims of remote access without installation are likely scams or illegal.