Are you planning “free camera” one that you can move separately from player character? If so you should split camera pawn from player character pawn.
For tera like camera, you need some logic behind scenes. Your camera should have 2 modes for rotation, one that is standard and follows orientation of pawn, and second that lets you rotate camera without rotating character. For swapping modes use some key (like alt, ctrl or shift, or RMB). When that key is pressed rotate camera with mouse X axis, when released rotate character instead.
This swap can be done with some camera arm setting that determines if it should rotate to owner pawn yaw or not.
So first test both modes manually see if flipping that property does what you need, then do event that turns it on/off depending on modifier key state. Btw. caps would be great here also.
Ps TERA has both modes: free and following character rotation.