使用递归，您可以尝试执行以下操作：

const accountSid = 'mySid';
const authToken = 'mytoken';
const client = require('twilio')(accountSid,authToken);

const numbers = ['whatsapp:+xxxxx','whatsapp:+xxxxxx'];

sendMessage(numbers);

function sendMessage(numbers) {

    // stop condition
    if (!numbers.length) {
        console.log("---------------------------------");
        return;
    }

    const currentNumber = numbers.shift();

    // send the message
    client.messages
        .create({
            from: 'whatsapp:+14155238886',to: currentNumber,body: 'hello'
        })
        .then(function (message) {
            console.log(message.sid + '\n');
            sendMessage(numbers);
        })
        .catch(function (err) {
            console.log(err);
        });

}

module.exports = app;

通过这种方法，消息将被依次发送。