It’s easy to tell apart a “usual” athlete and a weightlifter because weightlifters’ chest is lifted and expanded. It might sound stereotypical, but very often it’s not just their chest which wants to expand but also their personality in some way - they want to “control” the room and stand out. Expanded chest symbolizes power and confidence.
It’s normal that your chest expands when you train your back and chest muscles because those are large muscles and they participate in lifting and expanding the rib cage. If we’re talking about breathing though, this is not the best scenario because the chest naturally is kinda mobile and it should stay that way. When the chest is lifted and expanded, it becomes kinda fixed and the breathing therefore becomes more shallow and frequent, and you might experience a feeling of poor lung ventilation.
Weightlifters also usually hold their breath when lifting heavy weights but, as they’re doing it for short amounts of time, they often don’t feel the need to do it correctly. Athletes, on the contrary, have to think about breathing correctly all the time and can’t afford to hold their breath because that would worsen their results as the body wouldn’t get enough oxygen.
Athletes’ chest is mobile, but weightlifters chest - fixed.