If you played the demo, this chest may have taunted you. This is how to open the locked chest in Bar 99 in Stellar Blade on Eidos 7.

Now, armed with the code to the Legion Chest, head back to Eidos 7 using the Tetrapod and enter Bar 99 again. Input the code of 1228 and open up the chest.

Sifu players that are attempting to open the Code Door in the Club stage can find details on the location of the Club Code here.