https://docs.cloud.oracle.com/iaas/Content/Balance/Tasks/managingloadbalancer.htm?tocpath=Services%7CLoad%20Balancing%7C_____5 The essential components for load balancing include: * A load balancer with pre-provisioned bandwidth. * A backend set with a health check policy. See Managing Backend Sets. * Backend servers for your backend set. See Managing Backend Servers. * One or more listeners . See Managing Load Balancer Listeners. * Load balancer subnet security rules to allow the intended traffic. To learn more about these rules, see Security Rules. * Optionally, you can associate your listeners with SSL server certificate bundles to manage how your system handles SSL traffic. See Managing SSL Certificates.

Reference:
Can I set up Data Guard across Availability Domains? Yes, you can set up Data Guard in the same or different Availability Domains in a region. However, Oracle recommends that you set up your Data Guard configuration across Availability Domains. Can I set up Data Guard across Oracle Cloud Infrastructure regions? Yes, you can set up Data Guard across regions,
"but the Database Cloud Service Data Guard feature currently does not support it. " You can manually set up Data Guard across regions by logging on to your host and using DGMGRL. You must enable an internet gateway on the primary and standby DB system VCN for Data Guard to transport logs across regions. Learn more about DGMGRL.
To configure a Data Guard system across regions or between on-premises and Oracle Cloud Infrastructure DB systems, you must access the database host directly and use the DGMGRL utility.
https://docs.cloud.oracle.com/iaas/Content/Database/Tasks/usingdataguard.htm

You can scale up/down your Autonomous Database to scale both in terms of compute and storage only when needed, allows people to pay per use.
Oracle allows you to scale compute and storage independently, no need to do it together. these scaling activities fully online (no downtime required) in Details page Autonomous Database click Scale Up/Down. Click on arrow to select a value for CPU Core Count or Storage (TB).
Or Select auto scaling to allow the system to automatically use up to three times more CPU and IO resources to meet workload demand, compared to the database operating with auto scaling disabled.