You simply create an InputAction Object, and an Enhanced Input mapping Context. You can find both creation options when you rightclick inside your content browser and go to Input.
Inside the InputAction, you just do nothing… Cause it already is a bool.
Inside the mapping context, you add a new Mapping and select your previous created Input Action from the Selector.
As key, set the key you want. Again, don´t so anything else…
In your Blueprints, simply search for the Name of your Input Action and add that event… it has a “Started” (equals Key Pressed with that Settings) Output execution pin. Or else, use the “Triggered” output (Can fire each tick… be careful here).
The “Completed” output is the "Released"of the Key.