Thank you for posting your query on Microsoft Q&A, from above description I could understand that you are looking to rotate "certificate & secret" for Entra ID App Registration.
Please do correct me if this is not the case by responding in the comments section:
Currently we don't have an option to import or rotate certificate from Azure Key Vault for an Entra ID registered application, however we could a credential from Key Vault.
Using a Customer managed keys to encrypt data in your tenant using Azure Key Vault in another tenant. This could be done via a managed identity.
Once Setup, Now you could Navigate to your Keys in KeyVault and setup a rotation policy for the same:
Please do accept the answer and rate your experience if the above-mentioned suggestion works as per your business need