The last time I was a regular Sims player was, well, in the era of The Sims. The first one. Since those ancient days, it's my understanding that the series—or at least The Sims 4—has turned into a platform for some of the most exotic and enthusiastic sexual experimentation mankind has yet produced, largely thanks to its mega-popular Wicked Whims mod.
So I should not be surprised, but maybe lightly scandalised, that the Paralives community has quickly made a whole medley of NSFW mods for the game, then promptly made those mods the most popular among players (spotted by TheGamer).