Newby question / container for production and backup

Hi guys, Im learning about docker, I already have some images running.
For some downloaded images , like graylog / syspass, they includes the composer.yml files where you can set the “restart: always” sentence so , your containers are up when server reboots.
For other cotainers like “debian” oficial image, there is nothing similar mentioned.
So … How can I create a docker-composer file to launch this image everytime syste reboots and also asign a persistence storage/volume.
Is there a generic docker-composer.yml template ?

For container backup or in case my server crashes:
Should I keep a copy of each data volume ? Do I need to copy / keep other files?
Is there any proceadure for this ?

Thanks for your advice on this!