You will need to configure AUth0 to use OpenID COnnect (basically generate an id_token), when you go through the Auth0 login flow, you will get a an access token, etc. and and id_token.
With Postman, just use the header format:
Authorization: Bearer {id_token_here}
Your API will need to be configured to use OpenID Connect, and have your Auth0 endpoint and client app as a valid IDP.
You can find the Auth0 IDP URL and the Auth0 Client ID in the actual ID Token if you decode it with https://jwt.io, the IDP is the iss claim, and the client ID is the ‘aud’ claim