This is the same request as in bug 38263 from 2011. that was confirmed.
But that bug is spammed so let me move the issue here. 

Zooming presentation can be a standalone app on a limitless canvas, like Prezi. 
But more practical for LO is MSO approach with old PptPlex add-on that landed in MSO 2016.

As Gerry wrote: 
A zooming presentation features was added to MS Powerpoint : https://support.office.com/en-us/article/Use-Zoom-for-PowerPoint-to-bring-your-presentation-to-life-9d6c58cd-2125-4d29-86b1-0097c7dc47d7?ui=en-US&rs=en-US&ad=US

There are a number of OSS zooming presentation software, which might be helpful for the implementation of this feature in LibreOffice:

https://github.com/senshu/Sozi
https://github.com/impress/impress.js
https://github.com/tantaman/Strut
http://adityab.github.com/Awwation/

Jared also wrote: If there is ability to create "zoom areas" within slides, I think this could solve the basic function.  But ultimately a higher-level control to give navigation to the whole presentation would be the way to go.