How can I use fitMode on blog's customfeedwidget

I want to show the posters in full length like the picture below. (pic1)

But I’m using custom blog feed widget, ‘minimal’ to only show one category of posts.
The problem is, the ‘minimal’ blog feed shows the image in the post in a very short height like the image below (pic2)

How can I code it to show the poster image as it is in pic1?
Can I do this by using fitMode?
Answer is needed.