Yes, it's possible to to use Chartjs' Choropleth and Bubble Maps plugin with the Pro version. You can download the plugin js files to koolreport/chartjs/clients directory and set chart plugin like this:

\koolreport\chartjs\LineChart::create(array(
    ...
    "plugins"=>array("plugin_file_1.js", "plugin_file_2.js")
));

http://localhost/KoolReport/GitHub-documentation/chartjs/plugins/