Can we save db credentials in shared secrets of secrets manager and access in mule flow

Unfortunately at the current time Anypoint Secret Manager is not suitable as a general-purpose secrets manager. You can use Azure Key Vault or AWS Secrets Manager for this purpose along with a custom component to access them. There are available open-source components for both, or you can certainly create your own as it is reasonably straightforward.

Here are a couple of open-source components if you need them:

https://github.com/avioconsulting/mule-azure-key-vault-connector

https://github.com/grnhse/mulesoft-secrets-manager

Matt