I don’t think they are too close, but I would anticipate her needing to correct people at times. I picture her introducing herself to another child on the playground (where the child can’t see the name written). The other child might hear “[name]Sophia[/name]” because it is a name they are familiar with/used to hearing, know what I mean? So I can see her being called [name]Sophia[/name] at times by her peers, but I would think they would only have to be corrected once. She might get a few “Oh, I thought your name was [name]Sophia[/name]”, but [name]Sapphira[/name] is too gorgeous of a name to have that minor issue holding you back!
We had similar concerns about a name we like (this post inspired me to get other opinions, too!)…our concerns ultimately held us back from using it. Which honestly, I kind of regret, but I am still happy with our choice. And now I don’t have to worry about if it had ever been an issue or not (being too similar to some very popular names)