Criptograma Chests are a new form of collectible in Far Cry 6. These chests require you to find two Criptograma Charts to unlock them and retrieve the prize inside. There is one chest hidden in the scrapyard of the town Feroza in the Balaceras region. Check the map below for reference. Once you arrive in Feroza, head south, and you will find the chest next to a small building with an outhouse next to it.
While looking at the chest, head to the right. There is a shipping container. Walk around the shipping container to find a pile of metal and concrete scrap under a metal roof. On the other side of the pile of metal and concrete are two boards leaning against the concrete wall. Shoot them, and they will fall apart, revealing a hole. Go through the hole and turn around to find the first chart above the hole you crawled through.
To find the second chart, go back out of the hole you crawled through and turn left. Walk through the destroyed section of the green concrete wall. On the other side is a car with a pallet leaning against it. Destroy the pallet with either a gun or your machete to reveal the second chart inside the car attached to the steering wheel.
Now that you have both the charts, you can run back to the Criptograma Chest near the beginning of the area to collect your reward.