As far as I've seen there are no rules for True Drakes in Shadowrun 5th Edition. The rules for Drakes are detailed in Howling Shadows, and True Drakes appeared in previous editions. I would like to know if there are rules for them somewhere for 5th edition or plans to release them.
At present, there are no rules in place for True Drakes in 5th Edition. All reference in the books to Drakes speaks as if the "I'm a metahuman who spontaneously turns into a dracoform" is the only template that exists. In fact, there are no references to True Drakes at all, even in the Fiction sections.