shrill vs shout out

shrill is an adjective but shout out is not an adjective.

Word	Noun	Adjective	Verb	Adverb
shrill	No	Yes	Yes	No
shout out	No	No	Yes	No

As verbs, shout out is a hypernym of shrill; that is, shout out is a word with a broader meaning than shrill:

Other hypernyms of shrill include call, cry, holler, hollo, scream, shout, squall, yell.

shrill (adjective)	shout out (adjective)
of colors that are bright and gaudy
having or emitting a high-pitched and sharp tone or tones
being sharply insistent on being heard

shrill (verb)	shout out (verb)
utter a shrill cry	utter a sudden loud cry
	utter in a very loud voice