You need to find the Dying Light 2 Skullface safe code during the Gilded Cage side mission if you want to crack the safe as part of the Bloody Ties DLC. This particular quest is automatically unlocked as you progress, and you'll be tasked with finding Skullface's weakness by searching his room.
Like the safe codes (opens in new tab) in the main game, the secret—or code—won't just be left lying around, so you'll need to investigate if you want to get into the safe and complete this quest stage. So, if you're ready to get cracking, here's the Dying Light 2 Skullface safe code, as well as the clues you need to work it out for yourself.
Dying Light 2 Skullface safe code
Once you've made your way to Skullface's room, avoiding the patrolling guard along the way, you'll find the safe on a counter, next to some small wooden crates. You need to figure out the code and get inside the safe to progress further, so use your Survivor Sense to see points of interest around the room: of note is the poster with "999" on it, and the writing on the wall that says "02".
Put those numbers together and you'll get the Dying Light 2 Skullface safe code, which is "99-90-2". Once you enter the code via the dial on the safe, you can grab the map inside, which will prompt Aiden to contact Astrid and start the mission's next stage.
Some players have reported the mission bugging out and the safe not opening, despite entering the correct code. If this happens, try starting over from the last checkpoint to see if that fixes the issue.