Spectral Layers, iZotope Rx, ect. are for audio repair / restoration. For effects, (reverb, echo, chorus, ect.) there's loads of plug-ins available to purchase and for free. I know Sound Forge Pro includes alot.
like i said....an 'audio/music visualizer/spectrum' 😉 But yes for the effect/layer to make in AE it's called 'Audio Spectrum', anyway to answer your question as far as I know there is only BCC (boris continuum complete} that comes close with it called 'Beat Reactor', as far I played with it some time ago it had only one 'Spectrum'....
I'm also looking for a music visualizer effect to add to an audio only file, so that it can become a video file that can be uploaded to facebook.. Does one exist in Vegas? Or any VST?