Hello I hope I understood what you want cuz im in hurry right now.
I printed a crosshair at a specific point on the map with blueprints using ConvertWorldLocationToScreenLocation from the Player Controller and then drawed a texture at the x and y cords of the return. In blueprints it also returns whether the location is on the screen.
You can look for ConvertWorldLocationToScreenLocation in the PlayerController from the HUD class and Draw a rectangle.
If you want the edges to be smooth you would have to combine draw line functions and draw circle funktions.
Good luck!