You don’t directly control most of the contents within this object, however, as mentioned in the linked documentation, if you pass additional query string parameters when initiating the navigation to the hosted login page from your client application then these extra parameters will be available at
config.extraParams; assuming you processed the contents of the
@@config@@ into a variable named
config like it is shown in the documentation:
var config = JSON.parse(decodeURIComponent(escape(window.atob('@@config@@'))));
From your post it seems your goal is to pass additional parameters so you should focus on the contents of
config.extraParams after ensuring that you pass the additional data through query string parameters.