At some point during your Resident Evil VIII or Resident Evil Village playthrough, Lady Dimitrescu is going to start hunting you around the castle. During this time, you possess the Dimitrescu key, which unlocks the Special Chambers room. Have a look at the map below to locate the Special Chambers.
Once there, you will need to light two cradles to unlock/unblock the sarcophagus behind the iron wall. There is already one lit cradle behind an almost broken wall. You can break that wall with a Pipe Bomb which you can find in that same room.
After breaking the wall you can push the left cradle towards the lit one and light it up.
Now to light the final cradle you need to just use physics. But the execution can be annoying. Stand at the of the cradles, the one you just lit and the unlit and using shift run and push the lit one towards the wall and then swiftly push the unlit one towards the wall in exactly the opposite direction.
The two cradles will bound on the walls and will meet back at the center of the room where the lit one will light up the unlit one.
Sadly, I didn't make a video of this. But it's pretty simple in case you are wondering how to do it.
Doing this will unlock the sarcophagus in which you will find another eye key item.