It is not a plug in. It is a native Grasshopper component.
I don‘t want to be mean @zfq947254420,
but you created several topics searching for a component oder plugin.
Google will mostly solve your problem.
Just search for component name + grasshopper.
Example: https://www.google.de/search?q=split+argb+grasshopper&ie=UTF-8&oe=UTF-8&hl=de-de&client=safari
Most of the time Rhino.github.io will be your first result, where you can find the name/plugin/category etc.
Btw. You could double click on canvas or press space and type the name of the component. If it‘s there, for example with split argb, it‘s no plugin.