I’ve seen a few questions on AnswerHUB as well as on the forums on how to get a toggle shoulder-type camera for the Blueprint Thirdperson Template. While this is in no means perfect, it should be able to get you started so that you can tune/tweak it to your liking (as I said, this is a foundation for you to play with). There are some things like adding camera constraints while over-the-shoulder cam is active as well as making the character pawn animate and turn towards the camera when switching to the shoulder cam, but it’s a start.
Inside the Character Blueprint, you’ll need to create two reference points for the FollowCamera to move between, so I’ve created a Scene Component and called it DefaultCamera where the Default Camera should be.
Then I created another Scene Component called AltCamera and placed it where I wanted the shoulder camera to be. Both of these are children of the CameraBoom SpringArmComponent.
Essentially what I’ve done is create a Custom Event called ShoulderCam which is tied to an Event Tick. This feeds my Gate and whenever I hold (right mouse button) AimMode I transition to the AltCamera and automatically rotate my pawn in the direction of the camera which is controlled by the mouse (as noted, the character pops to the camera rotation but you get the idea). When I release right mouse, the camera moves back to the default camera location.
The end result looks something like this:
Like I said, it still needs some work but should point you in the somewhat right direction.