I let DD when she was that age. The algorithm goes to stuff she’s interested in extremely quickly so it’s dances, jokes and history. Mines politics and languages. I’ve never seen anything dangerous or dodgy on either account but I know it’s there so I guard her.
I think the most dangerous things are messaging apps like Snapchat. People pretending to be someone else and causing upset. You can tell a kid every eventuality to try and protect them from danger but the predators are one step ahead. DD had someone message her saying they were a teenager who was concerned they were gay and needed someone to talk to. She just thought he needed help. He sent her quite vulgar messages of his first sexual encounter a few days after.
im a big believer that until they can be trusted you should have access to their phone. You pay fr it after all. It’s not about invading privacy, it’s about keeping them safe and using an open channel.