Yes, Carol Peletier tragically loses her daughter, Sophia.
Sophia's death occurred early in the zombie apocalypse, during a time when Carol was still timid and lacked the experience necessary to protect her. Despite Carol later evolving into a formidable and highly capable survivor with one of the highest kill counts, the inability to save Sophia due to her initial inexperience likely remains a deeply haunting memory. This loss played a significant role in shaping Carol's development from a timid individual to the ruthless and resilient character she became.
Sophia's disappearance and eventual discovery as a walker in Hershel's barn was a pivotal moment not only for Carol but also for the entire survivor group, highlighting the brutal realities of their new world.