The first one that really comes to mind for me would be Cypress Zeta's Overwhored. Play as an ancient Overlord who's been asleep for an extended period of time thanks to some heroines, but has reawakened to conquer all the women and land that's rightfully his!
Also, IDK if this is really what you're looking for, but if you're okay with playing as a character who starts off somewhat good, but becomes neutral while trying to embrace an evil power, you could always check out Sierra Lee's The Last Sovereign. What I consider a masterclass in RPGM storytelling with some nice sex too. Though, the sex is mainly through text, so if you're okay with that...
Finally, is protagonist is technically a chaotic neutral character who fights against evil, but does technically do some pretty shady stuff in Bad Kitty Games' Harem Collector. A fun game with some pretty great RPG references.
Just a reminder though that only the first one has you playing a truly evil lord. The second one is a more neutral character who tries to use an evil power to fight evil, and the last one is mainly about an MC who is funny but also kind of a dick with the way he gets his girls.
TL;DR: Overlord by Cypress Zeta is what you're looking for, but I'd also recommend The Last Sovereign by Sierra Lee and Harem Collector by Bad Kitty Games.