Sophia with a lighter hair color:

And even lighter (+Tail):

I think the original color fits the bill of Honey-blonde (also a caramel/brwon/honey hue) with a bit of orange the best. These here work, too, though, I guess? If you imagined her hair more like this, here you go.

Sophia with short hair:

I'm normally more into longer hair, but this one is speaking to me and I had to share it. There are currently no plans for her to appear like this in the story (for now), but I think it's really nice to look at.

Don't forget to also look at the illustrations in Ch. 2.5 and 22.5 if you haven't already.