Hello,
thank you for the advice. Unfortunately this change is not effective. The element class is “attachment-portum-blog-post-sticky size-portum-blog-post-sticky wp-post-image” so I changed both the blog post image to false and the blog post sticky image to false.
Neither worked. I deleted the browser cache and tried on different browsers: the image is 2858 x 1328 and (http://www.dnra.it/wp-content/uploads/2018/11/Lo-studio2.jpg) and it is being resized anyways.
Any other hint please?
Since you have already changed the code, you can use this plugin to regenerate the thumbnails:
Another option is to delete the code controlling that thumbnail, it should be either the portume blog section image of the portum blog post image. Once you delete those then the theme won’t create thumbnails of the images.