how can i change the date formats in mongodb to %d/%m/%y from %d-%m-%y code example

Example: mongodb check date only without time

db.collection.aggregate([{
                $addFields: {
                    onlyDate: {
                        $dateToString: {
                            format: '%Y-%m-%d',
                            date: '$date'
                        }
                    }
                }
            }, 
            {
                $match: {
                    onlyDate: {
                        '$eq': onlyTodayDate
                    }
                }
            }
        ]);