Hello,
Thank you very much for choosing our theme and for contacting us.
The header does not have its own sidebar, at the same time you can create a customer sidebar in Dashboard > Sidebars, add the switcher widget and follow these steps to add this sidebar to the header:
1. You need to create HTML block: https://xtemos.com/docs-topic/html-blocks-usage/
2. Add widgetized sidebar element or widget (both WP bakery and Elementor has this element in the chart)
3. Add this HTML block in the Header builder: https://xtemos.com/docs-topic/how-to-add-and-edit-builder-elements/ you need to add HTML Block built with WPBakery and select the HTML block you have created from the drop-down list.
If you have any questions please feel free to contact us.
Best Regards