Anime ends on Chapter 264. You can start reading from chapter 265.
Manga chapter 264, page 21
Anime episode 12, the scene at 23:22
Some of user on reddit said
Aaaand it's a bad idea. I mean, a really BAD idea. You can't start reading from where the anime ended, you will be lost. Important plot points (I'm not talking filler here, I'm talking real important plot points) were skipped by ANY Berserk anime adaptation. I started reading from the end of the 1997 anime, you think I would be safe: I wasn't, cause I lost all the explanations given in Black Swordsman Arc regarding Apostles and God Hand. Berserk 2016 skips the Demon Baby, Berserk 2017 skips the Moonlight boy. And if we are talking about "normal" content that's been skipped...you'll lose the Wyald fight, Lost Children Arc, and tons of other stuff. READ FROM THE BEGINNING, I can't stress this enough. - BerserkGallery
That don't even matter when the anime won't even tell the same history as the manga .... and i'm not talking about adaptations, i'm talking about shit like skipping WHOLE major arcs, or just removing completely VITAL screens and even characters from the history ....Dracsxd