Where to get a 3d model which is already rigged but is writable & can be changed?

Where can I get a free rigged writable animation character or dragon which I can change however I want? I want to change the colour, sculpt, let it move & talk.
I want to learn it that way and do small projects on the side.

I saw reliable safe websites like: free3d&cgtrader.com, but it wasn’t what I wanted.