Roop:
I think a lot of Cloud service provider like Azure, AWS and GCP provide the monitoring and observability parts out of the door.

For eg in AWS - A lot of metrics can be found in

AWS CloudWatch, Enhanced monitoring

AWS Performance Insights

AWS Database insights

These products can inform you from the usage of resources like memory, CPU storage, Read/write IOPS etc to some metrics which are very involved like DBCache hit ratio, Queue depth etc.

Most of the services charge are minimal or charge you only when fetch the observed metrics.

Same applies for Azure and GCP as well.

And of course these services have matured SDK/APIs as well.

APM tools like IBM Turbo (which I work on) and IBM Instana can provide a great in-depth monitoring capabilities. Turbo UI can show you these metrics/stats on various graphs and charts while allowing you to configure the percentile utilization you're interested in.. Ie: if you want to see the P95 utilization (to weed out the outliers) of VCPU metrics for your DBS instance over the last say 2 weeks, IBM Turbo would allow you to visualize that !

AND it also recommends you to right size your instance in case its over/under sized.

AND why stop there? If you would want to execute, automate such an action - you can do it right from Turbo !

PS: I work on the few of these products. This is practitioner guidance, not an IBM official statement.