Question: I am in need of an iPhone app that will count down or up from a particular number for a visually impaired individual. 

For example if 60 is entered a voice would say 60,59,58,57 and etc. 

Does something like this exist for an iPhone 6?

Answer: 
I found this app "Voice Over Timer" which looks to be configurable to do close to what you want. 

AppStore Link: 
<https://appsto.re/us/TeCFM.i>

*edit* upon further review, it looks like the countdown can only be announced for the last ten seconds. The AppStore page mentioned a customization but it is a customization from among pre-determined options.
"Stopwatch - simple with voice speaking time" - that's the full name.