https://www.weareteachers.com/books-for-6th-graders/
There’s lots of interesting looking books at the link above, but you and/or your daughter could check with the librarians at her school or at your local libraries to get more tailored recommendations by giving the names of her favorites and what she’s finding too scary or sad. Librarians LOVE to match readers with books.
Also two series that might work or will soon:
The Fairyland Series by Catherynne M. Valente
The Wayward Children Series by Seanan McGuire