$and

Filter records that match multiple conditions simultaneously. The $and method is used to combine multiple conditions, ensuring that all specified criteria are met for a record to be included in the result set.

await Member.$search({
    $where: {
        username: {
            $and: [
                { age: { $eq: 16 }  },
                { userId: { $startsWith: '123' } }
            ]
        }
    }
});