A mixed girl has a box of magic chalk. If you draw a picture with it you can go into said picture.

[Lyra]

It's a short book. It possibly has the word 'Vally' in it. It was at least published in 2016. It was a book required by an Australian school.

[Rainbowheart]

Is this a picture book or a child's novel?

Is the mixed girl white and Australian aboriginal?

Is "Vally" a name, or is the word "valley" in the title?

[Angela]

The Garden of Empress Cassia by Gabrielle Wang?

[Molly]

Reminds me of "Journey", by Aaron Becker...but that's a picture book without words, which seems like it would stand out in someone's memory. It's also a series, but I'm not familiar with the other two.

Journey

PS—it's a really gorgeous book, even if it's not the one you're looking for! ;)