To get into the Bent Pyramid of Sneferu go into the side entrance of the pyramid. Follow the tunnels until you get to a dead end. Attack the wall and shoot the jar through the bars:
Then go to the back of the Bent Pyramid of Sneferu and climb up to the entrance. Push the shelves back and go past the shelves on the left. To investigate the tomb where Bayek killed The Heron in First Blood in Assassin’s Creed: Origins interact with the arrow on the ground. Hit the wall and go through:
Destroy the jars on the right and kill the snake. Investigate the mask on the ground. Investigate the bowl on the tomb. Investigate the box to the left of the tomb.