I want to display all the posts by the featured image of each post.
Is there a shortcode or can you give me some tips on how to achieve this ?
you can modify or create a simple posts loop with only feature image in there. so you could use something like :
then your CSS can be:
this should create a simple grid of feature images with a green border that will change to blue when you hover the image. obviously you can change the look of it by adding different styling but this should get you a good start point.