Microsoft pushed an update for Microsoft Photos with new Slideshow feature on Windows 10. The update is available for Fast Ring Insiders. As the feature name suggests, the Slideshow button starts the slideshow of your photos in the app.
However, You can not change the delay or play/pause the slideshow. The feature is limited yet and we can see improvements with the future updates. Microsoft also added some animation for opening the app. The current updated version for the Photos is 16.703010032.0.
You can download the Photos app by clicking here