When running the code below in ArcPro python window it works, but when ran in a stand alone script read into ArcPro it doesn't work...After talking with ESRI support, in order to change symbology the code has to be ran directly in the python window of ArcPro in order for it to work. That ArcPro doesn't have this capability just yet for it to be ran through a stand alone script. If you can look into this and make a stand alone script be able to run the arcpy.management.ApplySymbologyFromLayer(lyr, sym) that would be great!!!
for lyr in active_map.listLayers():
if lyr.name == "Parcel_Buffer":
sym = os.path.join(lyr_directory, "Parcel_Buffer_ArcGISPro.lyrx")
arcpy.management.ApplySymbologyFromLayer(lyr, sym)
elif lyr.name == "Parcel_Selection":
sym = os.path.join(lyr_directory, "Selected_Parcel_ArcGISPro.lyrx")
arcpy.management.ApplySymbologyFromLayer(lyr, sym)
elif lyr.name == "Parcels_in_Buffer":
sym = os.path.join(lyr_directory, "Parcel_Buffer_Intersect.lyrx")
arcpy.management.ApplySymbologyFromLayer(lyr, sym)
elif lyr.name == "Parcels_Sorted":
sym = os.path.join(lyr_directory, "Sorted_Parcels_ArcGISPro.lyrx")
arcpy.management.ApplySymbologyFromLayer(lyr, sym)
else:
"No symbol file for specified layer"
aprx.save()