What a coincidence 
Your objective is the combination of some of my recent approaches for other people! Hold on for a moment.
Alright! So is this your objective?
- The map can be freely navigated with the camera
- While not locked on, the player character’s location doesn’t affect the view
- The camera smoothly locks on the player charater on input
- When locked, only player character’s location determines the view
Here’s the setup, along with some extra stuff like zooming and clamping 
Create a character class blueprint for the player character, but do not add any camera or spring arm components to it.
Then create a pawn class blueprint for the camera and add a camera component to it. You can also set it a tilt directly from the viewport.
Here’s the Event Graph of the player character’s blueprint:
Above 
are the related parts to the control of the player character. Below are also inside the same Event Graph, but parts related to the control of the camera:
The timeline:
And the Event Graph of the camera pawn:
And finally, the collapsed graph for clamping:
Hope this helps! 