Without a GIS object instantiated, geometry operations will be attempted using locally installed geometry libraries, i.e., ArcPy or Shapely. This is what Aaron is referencing. If you don't have a local geometry library, the operations will return None (or possibly error).
If you don't want to or can't install a local geometry library, you can use the geometry service from AGOL or an ArcGIS Enterprise.
import arcgis
gis = arcgis.gis.GIS()
url = 'https://services.arcgis.com/V6ZHFr6zdgNZuVG0/ArcGIS/rest/services/NYCDemographics1/FeatureServer/0'
layer = arcgis.features.FeatureLayer(url)
query = layer.query(
where = '1=1',
out_sr = 4326,
geometry_precision = 6,
result_record_count = 10,
)
label_points = arcgis.geometry.label_points(
spatial_ref=4326,
polygons=[feature.geometry for feature in query.features],
gis = gis
)
print (label_points)