I would not expect them to know how hard it is to track a dragon or evade a giant as they don't exist in our world

However, unless the dragon is flying, I imagine their large size would result in obvious foot prints while their body would leave signs of broken branches and damaged trees and the like in forests and other heavily vegetated areas- if they existed. And, if they were flying and visible to the characters, well, they would also be able to be tracked through vision while in visual range.