Landing Pages allow Images to function as banners and extend to the horizontal edges of the layout area. Let's look at how to set up an image as a banner.
To set an image as a banner, hover over an image and click the blue Gear icon to open the Image Properties pop-up.
Check the Is A Banner checkbox and click Save (the checkbox is unchecked by default).
The image now automatically resizes and extends to the horizontal edges of the layout area.
The Right Proportion!
When you designate an image as a banner, there is no impact to the layout area size. However, if the layout area is resized, the banner image is resized proportionally (the image maintains its aspect ratio and resizes to the width of the layout area). Note that the image height may also resize, and this could push other items further down the page.