It's best to read about group by before trying these out. It will show you how results are formatted, the number of results returned, and how to sort results.
/works group_by attributes
The host_venue and alternate_host_venues properties have been deprecated in favor of primary_location and locations. The attributes host_venue and alternate_host_venues are no longer available in the Work object, and trying to access them in filters or group-bys will return an error.