Hi there,
first off – by default the theme will display the blog in a single column.
The Blog options module allows you to set those columns:
https://docs.generatepress.com/article/blog-content-layout/
So the recommended way today to design ta post layout like that is to use the Block Element – Content Template with the Free GenerateBlocks (GB) plugin – start reading here first on how Block Elements work:
https://docs.generatepress.com/article/block-element-overview/
And then check this out for creating your content template for your post archive:
https://docs.generatepress.com/article/block-element-content-template/
That design looks like a simple GB Grid Block ( 2 column ) in the first Column is a GP Dynamic Image Block set to the Featured Image, and in the second column a GB Headline Block set to the Dynamic Text type of Post Title.