Hopefully you’ll still be able to backup your device to your iCloud:
Settings > [Your Name / AppleID] > iCloud > iCloud Backup - set to ON
Once iCloud Backup has been enabled, assuming you have adequate capacity in your iCloud (you can subscribe to more space if needed), your device should automatically backup when the device is connected to external power and is locked - once a day. You can also initiate an immediate backup:
Settings > [Your Name / AppleID] > iCloud > iCloud Backup > Backup Now
You can see your backup and the last backup date/time here:
Settings > [Your Name / AppleID] > iCloud > Manage Storage > Backups
If you are unable to backup to iCloud, you can alternatively connect your device to your PC/Mac - and using iTunes create a local backup of the device; you will need to select a passcode for the backup if you wish to create a full-backup that includes encrypted sensitive data (e.g., your Keychain).
Here is an Apple help article that should clarify the backup processes:
https://support.apple.com/en-gb/HT203977
I hope this is helpful in resolving your query.