Yes. It's called lock-on. It is in keybinds under movements or under character settings under target tab too, but that one is for autoattacks only and we dont autoattack in PvP so I dont think it is that one.
If it isn't this option then its your general camera setting. If you slowly walk backwards when pressing back or S you have the camera setting (standard/legacy) where it snaps your camera to the target every time.