I automate everything that I possibly can. My backups are no different.

I have three different computers on my office desk, all running Ubuntu 19.04. What I do to keep all of my home directories in sync and backed up is simply, Dropbox. I have a Dropbox Professional account which gives me three terabytes of cloud storage with 180 day revision history. So on a new Ubuntu install, I remove all of the default folders in the home directory (Documents, Music, Pictures, etc), sync my Dropbox account and then replace the original directories to symbolic links that reside in Dropbox. This not only keeps all of my computers in sync, it keeps a copy current and offsite in the cloud and a copy of every single version of a file for 180 days. This is also handy to be able to get to every file on my computers from my iPad and iPhone.

For my offline backup, I simply have a recurring task in my task manager, Todoist for every month to take an external hard drive out of my fireproof safe, copy over the entire Dropbox folder and done!

For the hell of it, I also compress and encrypt the entire Dropbox folder and copy it over to my Google Drive of which I have unlimited storage.