Miss Ham (b.1990) grew up through the coming of the age of the Internet, through chat rooms, MSN, Facebook et al. Throughout that I used to have what would now be called spyware running to ensure her safety and, if necessary, help educate. I was scrupulous in never using the information I saw, or acting with the benefit of its knowledge (that is, I had to decide stuff as if I hadn't learned x and so), I would only have acted on the info as a last resort, I had to accept that kids would do stuff, like I did. That involved (somewhat dangerously) keeping any info learned from Mrs Ham as I am certain she would not have been able not to use the info, to this day she is unaware. There comes a point where you decide your child no longer needs that level of protection, so you remove it. I don't know the technical details of how you might achieve that level of monitoring these days, especially given the wide use of message encryption, but I suspect it will be achievable.
The phone as a device is only part of the story, it's what they do with it or other devices (xbox, playstation, iPad etc) that is far more significant. In this day and age, I suspect a phone at secondary age is almost essential for communication and security, let alone maintaining peer standing, which is a significant issue not to be ignored. Arguably final year in primary is a good time to get them accustomed to it, in Miss Ham's growing up age phones were not "smart" so I didn't have to address that, SMS text was the thing.
Moving beyond what is most people's general disquiet and concern over giving their child a phone, there are two significant issues to consider. The restrictive aspects: "I don't want my child to zzzz" tend not to work as well as people would like and, at least IMO, are often counter productive, call me a permissive parent if you would like, that's where my tendencies go. The first issue is, how can you stop your child becoming a target for theft? Well, you can't. I'd avoid a top end phone and get a respectable mid range android phone of some nature (Daddy! all my friends have got iphones!!
), if I needed to I would insure it, but self insuring is likely the most useful. The second is when they can use it. Good luck on trying to impose controls yourself, but schools are moving towards banning their use during the school day (the school I'm involved in governance recently adopted such a policy, which is working well).
Phones are a part of modern life, children will have to learn to navigate their use in the context of their lives. I'm just glad I don't even have to begin to understand TikTok.