Hi, I have heard that paid traffic will be included in direct traffic if auto tag, cost data have not been enabled. Is this true?
If you meant Google Analytics and Adwords data , Yes. You need to enable auto tagging to get Adwords traffic reported as paid. Cost data is for getting cost related metrics. You need to link your adwords and analytics data and enable auto tagging. Other option is to tag destination URLs with campaign tracking variables of Google Analytics (utm_source, medium, campaign....), but cost data will not be taken into GA.