In the Viewpoints panel, open the full details of the presentation that you want to present and select the blue "Present" button.
In presentation mode, navigate between viewpoints using the left and right arrow keys or the panel in the right-hand corner.
Exit presentation mode using the back arrow at the top left.
Click "Adopt this view" to exit the presentation and enter the current viewpoint.
TIP: it's possible to interact with Viewpoints during while in presentation mode. For example you can right-click to identify layers, hover over markups to view more detail and even open up markup attachments such as images and PDFs.