website neophyte …
Trying to set up blog pages …
i was struggling with image size at top of blog page via the main menu. Wanted to have full page width, and simply crop the top, as the image size was way too tall and took up most of the screen. Tried resizing, but ended up not cropping, but redistributed the image and enlarged the image itself within a smaller box. Then installed simple image sizes … and then regenerated thumbnails … which I clearly didn’t know why but was having no luck understanding the RIGHT solution.
When i did this, suddenly the blog page showed in two large columns … looks terrible. Tried to set blog and widget to full size, didn’t do anything.
I’m lost …
Hello there
Anything that makes changes on the blog page layout is available in appearance > customize, from this setting you can change all possible settings for blog page and blog posts
Sorry @rperry but the question is not clearly formulated 
can you simply tell me what is your goal? without anything else