I've seen some posts on Twitter from profiles claiming to be 'Trans-Age' i.e they identify with a different age...
transage.carrd.co/#faq
''Transage is an umbrella term referring to those whose age identity does not align with their chronological age. It's a label that encompasses a wide range of experiences. It includes those who identify as older than their chronological age, those who identify as younger than their chronological age, and even those who are outside of the age-binary (such as agen't or xenoage individuals).''