I guess that it depends of the task executed by the cron. Why would you want your cron to be executed in a container if it can be run on the Docker host?
If the cron script needs to be executed in a container, you can pass the cron script's command to the container and execute the container in the crontab of the Docker host.
E.g. in /etc/cron.d/my-docker-cron on the Docker host:
@midnight root docker run --rm mycontainerimage my-cron-task