Explanation
If a bare metal DB system requires more compute node processing power, you can scale up (increase) the number of enabled CPU cores in the system without impacting the availability of that system but you can't increase the storage If the original DB system VM shape uses a single node, running databases on the DB system nodes are sequentially stopped and then restarted on the new shape so not dynamic

An internet gateway as an optional virtual router that connects the edge of the VCN with the internet. To use the gateway, the hosts on both ends of the connection must have public IP addresses for routing. Connections that originate in your VCN and are destined for a public IP address (either inside or outside the VCN) go through the internet gateway. Connections that originate outside the VCN and are destined for a public IP address inside the VCN go through the internet gateway.
Working with Internet Gateways
You create an internet gateway in the context of a specific VCN. In other words, the internet gateway is automatically attached to a VCN. However, you can disable and re-enable the internet gateway at any time. Compare this with a dynamic routing gateway (DRG), which you create as a standalone object that you then attach to a particular VCN. DRGs use a different model because they're intended to be modular building blocks for privately connecting VCNs to your on-premises network.
For traffic to flow between a subnet and an internet gateway, you must create a route rule accordingly in the subnet's route table (for example, destination CIDR = 0.0.0.0/0 and target = internet gateway). If the internet gateway is disabled, that means no traffic will flow to or from the internet even if there's a route rule that enables that traffic. For more information, see Route Tables.
For the purposes of access control, you must specify the compartment where you want the internet gateway to reside. If you're not sure which compartment to use, put the internet gateway in the same compartment as the cloud network. For more information, see Access Control.
You may optionally assign a friendly name to the internet gateway. It doesn't have to be unique, and you can change it later. Oracle automatically assigns the internet gateway a unique identifier called an Oracle Cloud ID (OCID). For more information, see Resource Identifiers.
To delete an internet gateway, it does not have to be disabled, but there must not be a route table that lists it as a target.
AS per compute instances can connect to the Internet so you use egress no ingress

Explanation
A service gateway lets resources in your VCN privately access specific Oracle services, without exposing the data to an internet gateway or NAT. The resources in the VCN can be in a private subnet and use only private IP addresses. The traffic from the VCN to the service of interest travels over the Oracle network fabric and never traverses the internet.
To give your VCN access to a given service CIDR label, you must enable that service CIDR label for the VCN's service gateway. You can do that when you create the service gateway, or later after it's created. You can also disable a service CIDR label for the service gateway at any time.
For traffic to be routed from a subnet in your VCN to a service gateway, you must add a rule accordingly to the subnet's route table. The rule must use the service gateway as the target.