sit vs change posture

sit and change posture both are verbs.

Word	Noun	Adjective	Verb	Adverb
sit	No	No	Yes	No
change posture	No	No	Yes	No

As verbs, change posture is a hypernym of sit; that is, change posture is a word with a broader meaning than sit:

sit (verb)	change posture (verb)
serve in a specific professional capacity	undergo a change in bodily posture
be in a position in which one's upper body is largely upright and supported by one's backside
show to a seat; assign a seat for
take a seat
be in session
sit and travel on the back of animal, usually while controlling its motions
assume a posture as for artistic purposes
work or act as a baby-sitter
be around, often idly or without specific purpose
be located or situated somewhere