Reference:
https://docs.cloud.oracle.com/en-us/iaas/Content/Balance/Reference/sessionpersistence.htm

Explanation
Oracle Cloud Infrastructure automatically backs up your Autonomous Databases and retains these backups for
60 days. Automatic backups are weekly full backups and daily incremental backups. You can also create manual backups to supplement your automatic backups. Manual backups are stored in an Object Storage bucket that you create, and are retained for 60 days The retention period for manual backups is the same as automatic backups which is 60 days. So we cannot preserve the backup for 12 months
https://docs.oracle.com/en/cloud/paas/autonomous-data-warehouse-cloud/user/backup-manual.html#GUID-D95E

An Oracle Data Guard implementation requires two DB systems, one containing the primary database and one containing the standby database. When you enable Oracle Data Guard for a virtual machine DB system database, a new DB system with the standby database is created and associated with the primary database. For a bare metal DB system, the DB system with the database that you want to use as the standby must already exist before you enable Oracle Data Guard.
Requirement details are as follows:
- Both DB systems must be in the same compartment.
- The DB systems must be the same shape type (for example, if the shape of the primary database is a virtual machine, then the shape of the standby database can be any other virtual machine shape).
- If your primary and standby databases are in different regions, then you must peer the virtual cloud networks (VCNs) for each database. See Remote VCN Peering (Across Regions).
- Configure the security list ingress and egress rules for the subnets of both DB systems in the Oracle Data Guard association to enable TCP traffic to move between the applicable ports. Ensure that the rules you create are stateful (the default).