query vs sound out

query is a noun but sound out is not a noun.

Word	Noun	Adjective	Verb	Adverb
query	Yes	No	Yes	No
sound out	No	No	Yes	No

As verbs, sound out is a hyponym of query; that is, sound out is a word with a more specific, narrower meaning than query:

Other hyponyms of query include enquire, inquire, wonder, interpellate, examine, pump, check out, feel out, debrief.

query (noun)	sound out (noun)
an instance of questioning

query (verb)	sound out (verb)
pose a question	try to learn someone's opinions and intentions
	speak, pronounce, or utter in a certain way