do you need to have read the grisha trilogy before six of crows???
No, you can read each series on their own. They’re set in the same world and a few characters from the Grisha trilogy make cameos in Six of Crows/ Crooked Kingdom, but otherwise the plotlines are kept pretty separate. I went into Six of Crows after having read the Grisha trilogy so i did feel like I had a more thorough understanding of the political climate surrounding the Grisha from the get-go in SoC, but the book itself did a really nice job laying out what information you’d need to know on its own anyway. I’d say you can always pick up the Grisha trilogy later if you want to know more about the world and the Grisha army but it’s not necessary.
Also, tbh, I just enjoy Six of Crows a lot more than the Grisha trilogy anyway. This is just my opinion at this point but I feel like it’s just a stronger series all around. L Bardugo’s writing improves drastically book to book, and that felt really painfully obvious in the Grisha series. All the characters and subplots she introduced in the later books were sooo much more interesting than the bland protagonist the series was just kind of stuck with. In contrast, I think the cast and premise of Six of Crows were really a testament to how much L Bardugo had grown as an author. I would recommend it first, with Grisha trilogy as optional supplementary material. But some people liked the Grisha series more than I did, so take that with a grain of salt haha.