Add the highlighted nodes shown in the image below, location at the top of the image.

Next go to the BP_SmartAIComponent and create a new variable called MeleeDetectHeightOffset and set it to Float and set the default value to 40 and tick Instance Editable.

Next create another variable called MeleeDetectSize and set the type to Vector, then set X,Y,Z to 25 and tick Instance Editable.

Add the highlighted nodes shown in the image below, location at the top of the image.