Qlik Sense is "responsive", as in it detects the screen resolution being used and rejigs objects accordingly - so if you use it with smartphone screen resolution it will go into its smartphone mode.
You can emulate this on a PC / laptop by making your web browser window small so it is the same size as a smartphone.
If you are talking about an app for Qlik Sense (similar to the QlikView app for iOS), then Qlik is working on releasing one in September 2017. You can download this app and then bring up your dashboards and see how they behave. In theory they will be responsive because Qlik Sense is responsive. Please refer to the post Qliksense Mobile App.
Additional Information- If you want to see how the QlikView app for iOS works then here is the link https://itunes.apple.com/us/app/qlikview-mobile/id565126319?mt=8.