Blog template used for this https://colorlib.com/travelify/blog/ blog is actually “Blog Medium Images” instrad of “Blog Large Image”.
However, it will work only in blog page and won’t apply to archive pages such as category, date, tags and other archives. To change this you will have to edit content-extensions.php file like this: https://colorlibsupport.com/t/the-template-blog-medium-images/#post-3053
In most cases you won’t need this but just use the right Blog template and you will be ready to go.