There you go: https://www.digitalocean.com/docs/images/snapshots/

No, DigitalOcean cannot and does not provide a backup plan for droplets as due to the nature of how the their infrastructure works. It would be a sys-admins nightmare!

Backup plans are available to the end-user, yourself to setup and configure. You can create your own using space, volume storage, or the built in droplet snapshots/backup feature.

However this is up to yourself to do.

For example, one project I have running in one droplet is a website that has a cron triggered bash script that drops the database and copies the files of a site to a mounted volume daily. Additionally I am using the DigitalOcean snapshot/backup feature for the server to take a weekly snapshot.

Here is a great start to help with a backup strategy.
https://www.digitalocean.com/community/tutorials/how-to-choose-an-effective-backup-strategy-for-your-vps