To the best of my knowledge, one can't fade in and out a "show mouse pointer".
Neither can one fade in or out a "show modifier keys pressed".
The only transitional aspect of the Screen Recording Properties that I can think of is the Pointer Zoom.
My feature request is for there to be "build" menu options, similar to those on the Callout Action menu, for the Screen Recording Properties. Not a huge deal, but it would be nice and it seems like the technology might already be there.