How to get session after OTP confirmation of Signup in the package ' amazon_cognito_identity_dart_2 1.0.5 ' in Flutter?

I am unable to get session after the confirmation of user in AWS Cognito. amazon_cognito_identity_dart_2 1.0.5 I'm using this package.

final CognitoUserPoolData userPoolData = await _userPool.signUp(
      phoneNumber,
      cognitoDefaultPassword,
      userAttributes: userAttributes,
    );
final cognitoUser = CognitoUser(phoneNumber, _userPool);
final confirmation = await cognitoUser.confirmRegistration('otp here');

Is there any way to get session on signup without authenticateUser() !!