I need help with the renewal of certificates, clone creation and EC2 extension

If you are on anything other than a Basic support plan, then you can log a support call with AWS (if you don't pay for support then you're on Basic Support https://aws.amazon.com/premiumsupport/plans/ )

The steps to refresh your Aurora certificate are here https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/UsingWithRDS.SSL-certificate-rotation.html

Not clear what expanding an EC2 instance refers to. If you're wanting to add an extra disk(s) to it then the process is here https://docs.aws.amazon.com/ebs/latest/userguide/ebs-attaching-volume.html

If you mean growing an existing EBS volume(s) then look at this https://docs.aws.amazon.com/ebs/latest/userguide/requesting-ebs-volume-modifications.html and then this https://docs.aws.amazon.com/ebs/latest/userguide/recognize-expanded-volume-linux.html

If the volume you are expanding is the system disk on a Windows EC2 then this will help too https://repost.aws/knowledge-center/expand-ebs-root-volume-windows

If you're looking to uplift the EC2 instance type then this is a good place to start https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-resize.html

Could you expand on what you mean by creating a real clone (with switch) ?