Change time in datetime field using Arcade or SQL

[GISAdmin7]

I have a field with thousands of dates formatted like this: 11/12/2000 7:30:00 PM. I need to convert the time in each to 12:00:00 PM while leaving the date unchanged.

I can do this using Python like: !DateField!.replace(hour=12, minute=0, second=0). ArcGIS Online limits calculations to only Arcade or SQL. 

How can I change the times in AGOL?

[JakeSkinner]

@GISAdmin7 ,

Do you have access to ArcGIS Pro?  If so, you can add the feature service and use the python expression you have above in the Calculate Field tool.