A developer hasa sandbox configured with a service and its profile and credential.

To enable manual changes to the service URL from a sandbox environment in Salesforce B2C Commerce Cloud, the recommended approach is to use a Site preference dedicated for the service URL. By configuring a Site preference, the developer can easily adjust the service URL directly through the Business Manager without modifying the service profile or credentials. This approach offers flexibility and control, allowing changes to be made dynamically as required by different environments or specific testing needs.