You can back up a SharePoint Online site on demand.
Note: By default, you can back up all versions of SharePoint files and list items. To back up only the latest version, go to the backup plan page. In the SharePoint pane, move the Back up all file versions toggle key to the left.
From the navigation pane, go to Protect > Office 365.
The Office 365 apps page appears.
Click the app to back up a site.
The app page appears.
Select a site, and then click Back up.
A message prompts you to confirm submission of the backup job.