There's no such function in Qlik Sense. It's not really an GIS analysis tool like for example ArcGis.
I recommend you to try the map extension IdevioMaps.
IdevioMaps offers through its GeoAnalytics connector a wide range of operations on geometries, such as Within (which is exactly what you need), Binning, Cluster, Closer, Closest, Dissolve, Intersects and Simplify, just to name a few.
More info and live demos at QlikMarket: