Want to develop your own voice? Steal somebody else's first
For some reason, what is perfectly normal and reasonable in one area of the arts, no, in every area of the arts, seems strange and dirty for many writers. When somebody first learns to play the guitar, they learn to do so by copying somebody else. It might start by having a buddy show you how to play a particular chord but eventually it moves on to, 'I want to learn how to play the Deep Purple Solo' just like Deep Purple did.
Nobody balks at this. Nobody says, 'hey there pal, wait a second...you can't copy the Deep Purple solo because well, it's there's and that would be cheating.' Nope, instead a famous guitar solo, piano solo, fiddle solo (whatever) is held up as something that people want to copy, are encouraged to copy in order that people can learn to play well.
We need to do this more in writing. Particularly when people are struggling with the concept of authorial voice or style.
So clearly, writing a book about a boy named Barry who wants to grow up to be a Fizard and goes to a school named Bogwarts, is not what I'm talking about. But if you look at how Rowling crafts her dialogue, the kind of humor she uses, the sound of her sentences...and you try to copy the style of that in your own words? What could possibly be wrong with that?
If you've never written a story that sounds like a Roald Dahl story (and you almost certainly have not) then give it a try. If you've never written a story that sounds like Judy Blume, then absolutely give it a try. Take a look at the great authorial solos within the children's book world. Copy their styles, their voices.
And you know what happens? Paul McCartney may have learned to play guitar by listening to the great guitar soloists before him, but Paul McCartney sounds like himself. The Edge from U2 may have learned to play guitar partly by listening to Paul McCartney and yet The Edge sounds like himself. Alison Krauss may have grown up listening to Patsy Cline, and Dolly Parton and Loretta Lynn, and yet Alison Krauss sounds just like herself.
So if you're struggling figuring out your unique authorial voice and style, try copying a few others first. Eventually, you'll learn to sound just like yourself.