YOU have control over the phones...
You have control over what gets installed...
You have control over when they can use the phones...
You have control over who they call and text...
You have control over when they lose phone privileges...

I know a ton of parents who blame the phone and social media on their kid's behaviors... but in reality its the parent's fault.

Kids have access to the same stuff (social media, porn.. etc) without phones, and when you are not around. IMHO, You need to teach your kids the rules and expectations early.

My kids had phones early because we liked being able to check up on them (friends, sports.. etc). My kids also learned phone rules early and it made the teenage years easier.