I’m not sure that drag and drop features like wp bakery, element or or divi exist in Publii. But I don’t use those “premium templates”.
If you read carefully the description of the theme you’ll see :
In this theme you’ll find three different post templates to suit multiple needs; two standard post layouts, and a special split-screen layout for when the image is just as important as the text.
So I don’t think you can customize the theme in 1×4 or 2×3 without modifying the css by yourself. But Publii allows you to insert custom CSS. So, if you want I think that you can easily modify the default 2×1 layout to something else. But with CSS, not ic the theme settings.