as of now - there is no out of the box on demand for QS.
you can check for new features each time new release comes out. They are always annouced on community, in whats new section as well as release notes. I would not expect any special additional announcment for this feature.
If you asking about extenisons - they are not supported here and you can check with developer who built it.
cheers Lech, When applicable please mark the correct/appropriate replies as "solution" (you can mark up to 3 "solutions". Please LIKE threads if the provided solution is helpful to the problem.
"...Over the next year, Qlik will focus on adding remaining gap features from NPrinting 16 to NPrinting 18+ such as On-Demand for Qlik Sense®, advanced search filters, task notifications, variable filters, select excluded filters as well as variables in the email subject line and body. Additionally, Qlik is working to provide a migration tool to help customers migrate their reports, connections, filters and tasks from NPrinting 16."