This study is researching experimental (study) drugs called pozelimab and cemdisiran. The study is focused on participants who have Geographic Atrophy (GA) caused by Age-related Macular Degeneration (AMD). Geographic atrophy is a medical term that refers to later-stage cases of AMD which is an eye condition affecting central vision (what one sees straight ahead). The purpose of this study is to evaluate the progression rate of Geographic Atrophy in eyes of patients treated with cemdisiran alone or in combination with pozelimab compared to those treated with placebo. The study is looking at several other research questions, including: * What side effects may happen from taking the study drug(s) * How much study drug(s) are in the blood at different times * Whether the body makes antibodies against the study drug(s) (which could make the study drug(s) less effective or could lead to side effects)