To set up data for Blog Layouts, please follow below instruction:
Please click the preset file to download the corresponding "json" of the layout you want.
Open downloaded file in the text editor.
SELECT ALL and COPY.
From your Shopify admin, go to Themes -> Actions -> Edit Code.
Find folder Templates -> Open file blog.json -> SELECT ALL and DELETE -> PASTE the copied preset from the external file.
Blog: Default
Blog: Standard