Microsoft Office has a build-in XML reader application, so this can be used for XML files. 
This application isn't set as default when installed, and must be done manually.

  1. Open the Windows Menu (⊞ Win);
  2. Search for "Default Apps";
  3. In the search bar at the top, search for ".xml";
  4. Set Office XML Handler as the default application for this file type (see below);
  5. You can go back and d other same for other file formats like ".xlxml", ".docxml", etc should you wish to cover all bases.