Themes are applied to sites via the Advanced tab of the page properties for the 'en' page by Publisher or Web administrator user roles.
The One theme is the primary, branded, and accessibility compliant design template. The VTx theme is a child theme of One made specifically for the VTx website. The VTMag2 theme is available to anyone that has magazine content they'd like to organize and present on the web. Please contact us for additional magazine setup questions beyond the information covered in the linked documentation.