SAML Configuration NameID Format

When configuring an application in Okta to be SAML enabled, there is a field called Name ID format that controls the format of the SAML assertion’s subject. However, it seems that the value used for the subject is always the username in Okta. Is that true or is there any way to change which user entity field is put into the SAML assertion’s subject?

Thanks for your time.

Here is an image of the configuration screen I’m referencing: