Books for a strong reader… who’s 6

My 6 year old daughter is a strong reader. She just read the first two Harry Potter books independently and definitely had strong comprehension. She has been reading well for about a year now, but these books really sucked her in more than some of her other favourites. She quite literally couldn’t put them down and even cried when she thought Harry was dying down with the basilisk. She’s very much a six year old girl who loves fairies and unicorns and princesses but is now very focused on Harry. I will let her read the third book as well, but the fourth one has a jump in maturity that I think she isn’t ready for. She enjoyed the rainbow fairy, Ramona and beazus, magic treehouse, dragon girls books etc. but she found the story was much better in Harry Potter.

What exists that is a similar story quality and remains appropriate for a six year old? Whenever I look things up people seem to expect kids her age to still be reading graphic novels or learn to read books but she’s ready for the real stories. My parents had the same problem with me when I was her age, but I honestly don’t remember when I read the books I read in my childhood.

Happy for any suggestions!