Different theme options in same WordPress site?

I’ve finished building my basic website, which is all pages except for my blog. It’s located here. I’m using a 2011 child theme. It took me forever to get the look I want on my website, and now I have it. But in order to do what I needed on these pages, I had to choose a single-column theme option.

For my blog, this single-column setup is not ideal. I want a double-column setup there, and a footer and so on, so that I can have some widgets and supplementary information.

Is it possible to keep the single-column option for all the pages, and use a two-column option just for the blog?

I’m still kind of a beginner with all this, and I don’t really understand how to do much with php or template files. I’d be grateful for some simply-worded help. I’m hoping not to have to do a whole other WordPress installation, although if that’s my only option I guess I can. I just don’t like the idea of having two totally separate dashboards. Is there a streamlined way to achieve what I want?