No, there is no specific process you need to follow. As far as QWAC certificate renewal process is concerned. you can directly use the new certificate after it is issued but we would recommend the below from our end.
Ensure that the new certificate is issued by an eIDAS trusted Qualified Trust Service Provider (QTSP - eIDAS Dashboard) and contains the same organizationIdentifier.
We strongly recommend testing your new certificate before using it with your customers. This helps to verify that everything works correctly and prevents potential issues.
You can perform your tests in our sandbox environment to ensure the new certificate operates as expected. This allows you to validate the certificate without impacting your production environment.