Controlling what is seen in featured image

I want to have a bit of control in what is visible on the featured image.

my website is https://www.argonauts-bd.com

The front page image should have a picture of a lighthouse. I tried playing around with the dimensions of the picture even adding padding but I can’t get any control with what shows up as the background for the hero banner. Could you please help me, Kathryn?

Alex