I have two boys who are both late teens now , they're more tech savvy than I am and if they wanted to hide something from me , they'd easily know how to. I've learnt to let them show me if something concerned them , rather than poking my nose in and checking every 5 minutes , in previous years it's been drilled into them to be safe , don't use your real name on socials , don't have your photos/profiles public , make sure your profile pictures don't give anything away like location etc. Kids are more clever than we give them credit for sometimes and thankfully the high school they both attended gave lessons out on being safe online. They're both aware of how bad the internet can be. We've got many apps now that give parents much more control and half the time it's the parents that need the lessons on being safe online and not the children!