I know this is from 2018 but I thought it would be good to add this in case folks come here looking for the answer.
Also this link has some very useful calcs: https://www.esri.com/arcgis-blog/products/field-maps/field-mobility/common-calculated-expressions-fo...
// Create a function to convert meters to lat, long
// Source: http://www.maptiler.org/google-maps-coordinates-tile-bounds-projection/
function MetersToLatLon(geometry) {
if (IsEmpty(geometry)) {
return [null, null]
}
var originShift = 2.0 * PI * 6378137.0 / 2.0
var lon = (geometry.x / originShift) * 180.0
var lat = (geometry.y / originShift) * 180.0
lat = 180.0 / PI * (2.0 * Atan( Exp( lat * PI / 180.0)) - PI / 2.0)
return [Round(lat, 6), Round(lon, 6)]
}
// Call the function and return the latitude or longitude value (change the 0 to a 1 for lon)
MetersToLatLon(Geometry($feature))[0]