Convert json DateTime format

My understanding of JSON Dates is that it is the number of milliseconds from a reference date of 1/1/1970. Therefore, I would strip out all the text characters, if you need assistance with that, let me know but you could do it with a MID that grabs the first character after the ( and grabs the number of characters up until the ). Make sure it is a number format and then you can use the following DAX:

Date = DATE(1970,1,1) + [JSONDate]/1000/86400

Basically, divide by 1,000 to get seconds and then by 86,400, the number of seconds in a day (you could just divide by 864,000. This gives you the number of days since 1/1/1970 and then you just add that to a date of 1/1/1970. I got back "3/7/2016 1:00:00 PM"

I would not recommend to do the transformation in a DAX calculated column.

You can do it with Power Query by Transforming an existing column.

The step to execute to do the transformation

= Table.TransformColumns(#"<previous step name>",{{"<column name to update>", DateFromJson}})

The code of the Power Query custom function

let DateFromJson = (date as any) as any =>
     let
        input = if date is null then "/Date(00000000000000)/"else date,
         Stripped = if Text.StartsWith(input, "/Date(") and Text.EndsWith(input, ")/") then Text.Range(input, 6, Text.Length(input) - 8) else error "Not a date",
         Position = Text.PositionOfAny(Stripped, {"+", "-"}, 1),
         Parts = if Position < 0 then { Stripped, "0" } else { Text.Range(Stripped, 0, Position), Text.Range(Stripped, Position) },
         NumberParts = { Number.FromText(Parts{0}), Number.FromText(Parts{1}) },
         Result = Date.FromText("1/1/1970") + #duration(0, 0, 0, (NumberParts{0} + 36000 * NumberParts{1}) / 1000),
        output = if Date.Year(Result) = 1970 then null else Result

     in
  output 
 in DateFromJson

How I can convert this format "2019-10-14T19:46:53.2751336Z" to "2019-10-14 19:46:53"?

Thaks!