Open a support service request with MOS option is available to paid accounts. Customers using only Always Free resources are not eligible for Oracle Support. Limited support is available to Free Tier accounts with Free Trial credits. After you use all of your credits or after your trial period ends (whichever comes first), you must upgrade to a paid account to access Oracle Support. If you choose not to upgrade and continue to use Always Free Services, you will not be eligible to raise a service request in My Oracle Support.
In addition to support for technical issues, use My Oracle Support if you need to:
* Reset the password or unlock the account for the tenancy administrator
* Add or change a tenancy administrator
* Request a service limit increase
Reference:
https://docs.cloud.oracle.com/en-us/iaas/Content/GSG/Tasks/contactingsupport.htm

Oracle Compute Shape is coming with predefined or customize the number of OCPUs that are allocated to an instance. The amount of memory, network bandwidth, and number of VNICs scale proportionately with the number of OCPUs.
Reference:
https://docs.cloud.oracle.com/en-us/iaas/Content/Compute/References/computeshapes.htm

You can open a support service request with Oracle Support
To create a service request:
Go to My Oracle Support and sign in.
If you are not signed in to Oracle Cloud Support, click Switch to Cloud Support at the top of the page.
Click Create Service Request.
Select the following from the displayed menus:
Service Type: Select Oracle Cloud Infrastructure from the list.
Service Name: Select the appropriate option for your organization.
Problem Type: Select your problem type from the list.
Enter your contact information.
Enter a Description, and then enter the required fields specific to your issue. For most Oracle Cloud Infrastructure issues you need to include the OCID (Oracle Cloud Identifier) for each resource you need help with. See Locating Oracle Cloud Infrastructure IDs for instructions on locating these.
Reference:
https://www.zerowait-state.com/blog/create-sr/

In OCI a budget can be used to set soft limits on your Oracle Cloud Infrastructure spending. You can set alerts on your budget to let you know when you might exceed your budget, and you can view all of your budgets and spending from one single place in the Oracle Cloud Infrastructure console.
Budgets are set on
* Cost-tracking tags
* Compartments (including the root compartment)
Reference:
https://docs.cloud.oracle.com/en-us/iaas/Content/Billing/Concepts/budgetsoverview.htm