This one is fairly simple, just click on the springarm and enable camera lag, tweak the value to preferred setting:
To rotate the camera using a keypress, simple enable camra rotation lag, create a new bool variable (IsInverted, default value is false) and add this anywhere on the character:
To fix the orientation of the character, because the camera has been rotated and basically inverted the controls, add this to the WASD logic:
That’s it!
FPS Game Starter Kit 