That kids can be excellent mimics and have a sense of humor that is sharpened by an un-ironic appreciation for the absurd?
Sure. All kids do adult things before they're adults; it's actually a part of BECOMING an adult!
Example: A kid cradles a doll or stuffed animal, pretends it's a baby. Has a tea party. Plays "Army Dude". Tells their parents with absolutely sincerity that need a time out.
The list is long.
A parentified child, however, may exhibit different adult-like behaviors that suggest they're in a non-developmentally appropriate role within the home.
It's apples and oranges, Anon.