How to add "MQTT Protocol" Plugin to RabbitMQ?

You can use Amazon MQ service. AMQP and MQTT are available there

https://aws.amazon.com/blogs/compute/deploy-and-publish-to-an-amazon-mq-broker-using-aws-serverless/

Amazon MQ for RabbitMQ doesn't currently support the MQTT plugin. Here is the list of supported plugins.

https://docs.aws.amazon.com/amazon-mq/latest/developer-guide/rabbitmq-basic-elements-plugins.html

As an alternative, you can use MQTT with Amazon MQ for ActiveMQ.