In aws you can change the CPU power of your instance by changing the instance type[1],
depending on the instance type you choose, you will be able to Increase or decrease the number of CPU cores of your CPU.

In order to compare between instance types available on aws view : https://aws.amazon.com/ec2/instance-types/
To change your instance type follow the steps in this guide : https://aws.amazon.com/premiumsupport/knowledge-center/resize-instance/

Hopefully this answers your question.

Reference : 
[1] https://docs.aws.amazon.com/AWSEC2/latest/WindowsGuide/ec2-instance-resize.html