Final answer:
The statement is incorrect; custom connectors can be used even if a standard connector is available, particularly when customized functionality is required that standard connectors do not offer.
Step-by-step explanation:
No, the statement that a custom connector cannot be used if a standard connector for the service is available is not correct. While standard connectors are provided as a first resort because they are pre-built and maintained by the service provider, there are scenarios where one might need to use custom connectors to meet specific requirements that are not covered by the standard connector. Custom connectors in technologies such as Microsoft Power Automate or other integration platforms allow for customization and flexibility when the existing connectors do not provide the necessary functionality or when a more tailored solution is needed.