I am looking to add a left and right sidebar on desktop. However when I enable sidebars in customise > layout > sidebars they appear inside the content container. I would like them to appear on either side of this container. How should I achieve this?
You can’t move them outside of the Content Container without custom development of the theme templates.
If you increase the Container Width and change the Layout to Separate Containers in Customizer > Layout > container – it should give you the effect you’re looking for.