Much of the literature for educators treats metacognition as a separate type of learning. Winne and Azevedo (2014) point out that metacognition is simply learning about one’s own learning, so it is not different from learning about other phenomena. The same theories and models that describe cognition describe metacognition. For example, when new to a field, a learner must expend cognitive load thinking about what they know and how it can be used. With greater expertise, metacognition becomes more automatic. This is the same effect we observed with scaffolds, as learners become more expert, they need them less.
Reference
Winne, P., & Azevedo, R. (2014). Metacognition. In R. Keith Sawyer (ed.), The Cambridge Handbook of Learning Sciences (pp. 63-87). Cambridge University Press.