Goody

Customize → Category

This is category page eg :Category Demo in here you can setting layout of this page

So when you in the Customize then you should click to Category

Then click to the Blogs Categories.

Sidebar Layout

Right Sidebar.

Please back to Widgets → Blogs.

Post Layout

You can setting layout posts for yourself

List Post.

Grid Post.

Transparent Post.

or you can use post layout with sidebar layout e.g

That's it!