Identity Server 5.4.0 provides more control over issuing id tokens and user claims for client-credential grant type. To facilitate this, the following configurations should be added to identity.xml in order to register new ScopeHandlers and ScopeValidators.
By making <IdTokenAllowed> 'true' or 'false' along with the above configuration, you can turn the issuing id tokens on/off for the grant types with 'openid' scope. (By default IdTokenAllowed is set to 'true', you can allow it to issue id_tokens for all grant types with 'openid' scope). By making this false, you can stop issuing id tokens. Anyway for authorization_code, you cannot turn off issuing id tokens.
By making <IsRefreshTokenAllowed> 'true' or 'false' along with the above configuration, you can turn the issuing refresh tokens on/off. (By default IsRefreshTokenAllowed is set to 'true', you can allow it to issue refresh tokens for all grant types). By making this false, you can stop issuing refresh tokens.