The web part is a specialized widget to display a Microsoft Visio diagram in a modern SharePoint page. It is somewhat similar to the “Visio Web Access” web part in “classic” SharePoint.
In addition to the stock “File Viewer” web part which you could use to display Visio diagram, this one features the following:
File browser, specific to Visio diagrams
You can specify which page to show first. You can specify either page name (like “My Second Page”), This only works if the diagram has more than one page. In case the page you selected does not exist, it will default to the first page.
Select default zoom level