We monitor his phone. So far he's been responsible with it. I realize that could change, but so far so good.
Also he knows no Social Media apps. None, period, zip. He also has to ask my permission for any app he wants to download and so far it's just been Hudl and another football plays app. I get a notification on my phone when I get a permission request. If I don't enter in a password he doesn't get to download the app.
I realize each kid might be different. Our daughter is in the 5th grade. She might or might not get a cell phone based on if we think she can handle it. She's a lot more emotional than her brother. Social media is an absolute disaster for teens, but even more so for teen girls.