Right now i have a short stem ( 70mm) thinking it would help the reach ( the bike is a 54 and i'm 5'9 but it feels a little big to me )

Wondering if going back to a 100cm stem would allow my arms to be further from under my body and make my arms less vertical would help any?

( and fwiw my bike is a fuji sst, not really a comfort bike by any means )