This page of our guide to Wolfenstein: Youngblood contains valuable tips on how to open a red box (red crates with concepts). As a reminder, red crates are one secret that you may find during your progress with the game. Each box contains silver coins and concept art. Its opening is also rewarded with experience points.
You can see an example of a red chest on the picture. You will encounter them from the second mission of the game - Riverside.
Every red box is locked. You can't break it, you just have to put the proper four-digit combination.
Look for floppy disks when you are investigating around a red box. With each new diskette, you find, reach the Floppy Terminal to decode it.
Decoded messages can be various, but they can contain, among other things, ready-made combinations. In the example from our picture, up to three different codes for red crates were stored on a floppy disk.
After obtaining the code, return to the red box. The correct code will be shown on the display, so you just need to rewrite it.