Partial Rendering of URL

I have got only link of documentation for Partial Rendering that is
is there any other documentation of the steps to create or example on the GitHub which I can refer to, also include helpful Enterprise Documentation Links.

what are you missing? It works out of the box there is no setup needed.

what is out of box here…? Please explain
Do you have to do a Rest Call for this…?

you can use REST or just call url as described in your browser

few examples: