Policies are rules to apply settings to queues/exchanges that match a pattern. An example below is declaring a policy to apply an ack/acknowlegment timeout of 300,000 ms (or 5 minutes). By default, the value is 30 minutes.
docker exec -it rabbitmq rabbitmqadmin declare policy \
--name ack-timeout-demo \
--pattern "^ack-timeout-demo$" \
--apply-to queues \
--definition '{"consumer-timeout":300000}'