The most common Korean word for “if so” is 그러면 (geureomyeon). 「if so」는 한국어로 그러면.
Learn 그러면 free — flashcards, audio and review →「그러면」 단어장으로 무료로 외우기Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato