In tests the scenario that you asked. The timeout of the request is 5 minutes, which was defined in the client
On the Client-side Timeouts
SendTimeout – used to initialize the OperationTimeout, which governs the whole process of sending a message, including receiving a reply message for a request/reply service operation. This timeout also applies when sending reply messages from a callback contract method.
ReceiveTimeout – is not used
On the Service-side Timeouts
SendTimeout are the same as on the client
ReceiveTimeout – used by the Service Framework Layer to initialize the session-idle timeout which controls how long a session can be idle before timing out.
See https://learn.microsoft.com/en-us/dotnet/framework/wcf/feature-details/configuring-timeout-values-on-a-binding