book series like attack on titan (not manga series)

i love love love love aot so much and i'm searching for another series that gives me the same feeling. just anything that reminded you of aot in any way and feel free to explain why!

i really like how in aot, by the end, the story became so much bigger than what we thought it was at the beginning. so many secrets and plot twists and that i still don't fully understand.

bonus points if the series longer than 3 books and all the books are good. i love a long series but not when stuff begins to feel like filler.

thank you in advance!!

(eta, im anticipating people suggesting the poppy war trilogy, which i have already read and absolutely loved. to this day it is the only other series that has made me feel the same way. so if you have recommendations more similar to this series id also appreciate that!)