Displaying a cone range can be done by simply resizing a cone sprite. Changing the angle is a little trickier, but I would just create a bunch of animation frames with as many different fan angles as I need.
If you need to show the cone of view WITH line of sight and obstructions... that is a rather advanced topic/technique. If this () is what you're looking for, I'll leave you with a few links:
You may want to compromise and just simply show the range and angle with a translucent cone sprite, and let the game handle LOS... showing LOS can be very tricky.
Alternatively, you might want to look into the shadow light/caster behavior, which may give you the effect you're looking for.