"The big owl is sad."
Translation:큰 부엉이가 슬퍼합니다.
No. If you are talking in third person (about something/someone else’s feelings or wants) you have to use -해요. It’s because we are basically saying they are acting that way. We don’t actually know the feelings or wants of another person or thing so by saying 슬퍼해요 or 고 싶어해요, the korean language gives that respect even though in English we’d just say he is sad or he wants pizza while in korean it’s almost like he is acting sad or he is acting as if he wants pizza.