TL;DR
Join a synced session presentation in the default split view, enlarge it for a bigger display, and minimize it to return to the session feed.
Overview
Use full-screen mode during a session to show your the presentation more clearly and help you stay focused. This view gives you a more immersive experience.
Maximize a Presentation
When a presenter syncs a presentation during a session, it appears on part of your screen by default. The rest of your screen shows the session feed.
To view the presentation on a larger screen, click the Maximize presentation button.
Minimize a Presentation
To return to the previous view, click Minimize presentation.