There are many arguments on this. Although it's true that phone can keep children company when their parents or friend can't, but it's also wrong to keep children playing with their phone when they're with friends, this can bring to phone addiction.
The first argument that supports children owning phone is that, phone is a good company to make children quiet, so that children won't behave irritable like screaming all over the house.
On the other hand, phone can bring a children to addiction, for example if they're already addicted when they have to dissmiss the use of phone in a plane, what they do is something irritable to others like crying and screaming while begging for their phone to be back.
The second argument that supports is, it's easy to not make children be addicted to their phone such as accompany them once to thrice everyday for at least 5 hour, and make sure that children won't use phone on a specific day to refrain addiction.
A further argument about this is, it's not easy to make children obey once they introduced themselves to internet and will make them bratty instead, also when a children own a phone and they played with it everyday then the radiation of which the phone provice will be channeled to the children's brain which if continuous will be dangerous for the children health.
In conclusion, I do think that it's okay for a children to own a phone because I myself owned a phone when I was below the age of 10, and it did help with loneliness of your parents not being with you everyday
