db.user.aggregate(
 {
    "$match": { 'phoneInfo.verifiedFlag': true}
},
{
    "$project": {
           yearMonthDayUTC: { $dateToString: { format: "%Y-%m-%d", date: "$createdOn" } }

    }
},
{
    "$group": {
        "_id": {day: "$yearMonthDayUTC"},
        count: {
            "$sum": 1
        }
    }
},
{
    $sort: {
        "_id.day": 1,
    }
})