Changing Time Zone from UTC to Current Location Time Zone

I'm trying to convert a date/time field (Purchase_Date) from UTC to my current systems time zone. I've tried creating a custom comun and using Power Query M function DateTimeZone.LocalNow(Purchase_Date). When I do this, I get an error, "Expression.Error: 1 arguments were passed to a function which expects 0." It initially loads as a text value, but I still get this error when I change it to Date/Time/Timezone. Does anyone have any suggestions?