Children's Booksky, help me out? Series for a bright turning-10yo who has read the XX Treehouse, Wimpy Kid etc, getting into the Phoenix comic, that sort of thing. My son's aged out of middle grade and I am out of the loop on new books!
My 11yo says City of Secrets, My Hero Academia, & the Legend of Zelda manga series. (she's very into anime) I also strongly rec the Rick Riordan presents books-- haven't found a dud yet-- and Kelly Jones's Saeurkraut & her Unusual Chickens duo
Does it have to be fiction? Because Greg Jenner has some good history books for kids: Totally Chaotic History
Seconding all the recommendations for Rick Riordan novels. I believe I spotted someone pointing out the Amulet graphic novels. Those are really good! I don't think I saw Lockwood and Co., or Bartimaeus by Jonathan Stroud in other recs. Those might be good transition books.
Ten? The Hobbit. Five Children and IT. The Lion, the witch and the Wardrobe.
The Septimus Heap books by Angie Sage were fun
Lots of great suggestions in other comments (Wings of Fire, Timmy Failure, Mysterious Benedict, Spy School) to which I'd add that if he's OK with female protagonists, Jennifer A. Nielsen's historical fiction novels were a huge hit with my daughter + most of her friends back in 5th grade.
Percy Jackson? There are 4 different series so loads of books. The stories are really good, and very inclusive. There is also a Disney After Dark series that my kid ate up.
The Rick Riordan Presents books are generally terrific. My kid’s favorite was Race to the Sun, but that one is stand-alone. She started getting into the Wings of Fire series around that age, that one has tons of books. Tapper Twins & Spy School are two other series she liked at around 10.
Artemis Fowle by Eoin Colfer Bone by Jeff Smith