I'm looking to create a layout like the below, which is enabled by the Stackable plugin.

I know exactly how I would do this if I was using CSS Grid, but because I want this to be easily drag-and-droppable by the client I'm making the site for (instead of asking them to write code), I'm looking for the best way to do it using Blocks.

I don't especially think that signing up to Stackable and paying a yearly subscription, for one small feature, is the best solution, so would appreciate if anyone has any suggestions on how to do this, or if there is a plugin available with this capability.

Thanks