Needs Jetpack, Slideshow Block documentation on Jetpack.com

You get a choice of transition and the slideshow can be set to auto with a choice of timings. The example below has a fade transition and plays automatically with a three second delay.

Coloured figures of the birds of the British Islands / issued by Lord Lilford.
London :R. H. Porter,1885-1897.
http://biodiversitylibrary.org/page/34524579 Public Domain images.

Block Setting Sidebar

The settings are unambiguous.