There are 2nd person cameras in some games including FPS games. Some replay data allows you to see your opponent's POV as they're scoring a kill on you, etc. Some have a respawn burn time that also allow you to see the action from another player's perspective.
The main thing is 2nd person perspective means you are now the observer, seeing action through another player's POV rather than the controller.
It's also possible to do a 2nd person narrative cut scene, seeing the action, not necessarily through another player's perspective, but through the perspective of a NPC as they are looking at or interacting with your character.
As a play mechanic, it would have to remain a passive play mode ("observer mode") as the instant you were able to assume control of the NPC or other character while viewing the action through their perspective, you would in effect become that second person, making the game a first person perspective game once again.
