With all of the collected DNA from most of the human species made available from the COVID tests, they can engineer the perfect breed of humans, in their image. Unfortunately, we aren't very good at gene editing yet, so anything they try to produce beyond simple selective "breeding" will fail, and could cause total destruction of the human species over time. The last time this happened, it is said that Enoch called out to the good angels to intervene, and they did, and they killed all of the abominations, and buried the bad angels, who were responsible, beneath the Earth.