Based on the provided knowledge sources, there is no direct mention of fetching a trait's default value using an API call during user registration. However, traits are part of the user identity and can be included in the registration process. For example, when registering a new user using the

/self-service/registration

endpoint with a

POST

request, you can include traits in the request body. The response will include the user's traits as part of the user's identity. Here is an example of how to include traits in the registration request:

bash curl -s -X POST -H "Content-Type: application/json" \     -d '{"traits.email": "[[email protected]]", "password": "__MY__PASSWORD__", "method": "password"}' \     "$actionUrl" | jq

And the response will look something like this:

json {     "session_token": "UA8rB8ydXyMyiIWcX8VeSWjUB7Z21YF1",     "session": {       "identity": {         "traits": {           "email": "[[email protected]]"         },       }     }   }

In this example,

traits.email

is a trait that is included in the registration request and returned in the response. However, this is not fetching a default value, but rather setting a value during registration. For more information, you can refer to the [Ory Kratos documentation](https://www.ory.sh/docs/kratos/self-service/flows/user-registration#registering-new-user-information).