Isadora doesn't ship with any VST plugins, rather it now supports a huge array of plugins available from 3rd party vendors. 
A little searching and you can find hundreds of free (or paid) vst3 plugins (note vst3 is important, some older plugins in vst2 format will not work).
this page lists many free vsts: Free VST Plugins - List w/Search Function, OS Compatibility, & Tags

Once installed there is a new panel for managing these plugins. (learn about this here: Managing VST Plugins in Isadora)

Along with support for these plugins, Isadora now offers a new 'Audio' patching type, and the additional of numerous Audio actors, for input, mixing, routing, analyzing, and output.
Supporting a multi-channel real-time mixing.

Perhaps, I need to make an intro video tutorial tht supplies links t a few free vsts, and walk through using a few simple audio effects. 
You can find a range of short audio tutorials on our youtube: troikatronix - YouTube