$capitalize

Update records by capitalizing the first letter of a string in a column. The $capitalize method is used to modify text fields by ensuring the first letter of each value is in uppercase, making it useful for formatting names, titles, or other similar data.

await Member.$update({
    $where: { 
        age: { 
            $eq: 16 
        } 
    },
    $update: {
       $capitalize: {
         username: true
       }
    }
});