Searching for a specific plug-in

Hello everyone ??

I’m trying to find a specific plugin, to gradually load a small box, at the bottom-right of the page, when my visitors reach the bottom of a page of my blog. In that box, there would be one or two links to other posts of mine, in order to keep the visitors onboard.

Several newspapers have started doing so, and I would like to make use of that feature (and of course, when I write it, I’m having trouble finding even one of them using that idea ?_? I only recall one right now, open a random page ot the French website https://www.rue89, and scroll down).
And I’d be interested in doing the same ??

Thank you very much if you could point me to a plugin doing that !

Or, even, if you know of the proper search terms to use in order to find that kind of plugin, that will be great !
I’m afraid my google-fu is too poor to allow me to find anything :-/

Thank you,
Sabinou