In a century that gave us Hitler, Stalin, Mao and Pol Pot, the worst a woman could manage was Mrs Gandhi's State of Emergency and her compulsory sterilisation of 10 million men.
Pol Pot allegedly killed 'between 1.2 million and 2.8 million' people, Mao about 1.5m, and I don't know the total Nazi death toll (about 7 million Jews alone, likely more).
Sterilising men obv isn't the same as executing them, but the overall impact on society could be close in terms of how many lives were prevented from ever coming into existence by the parents being sterilised.
Worryingly, India is still trying to sterilise men and there was a push in February of this year.
I don't think it's a good comparison, because dictators don't just focus on persecuting one sex like Gandhi did. This is much more gendered violence and had it been a man sterilising 10m women we'd probs have heard much more criticism (especially if it was still happening).