@SweetVirgo23 The only settings that would have an effect here are those that have to do with anti-aliasing. Vertical sync is completely unrelated. If you're curious, it tells the GPU to wait until it has fully rendered a frame to send that data to the monitor, thereby avoiding the monitor displaying parts of two different frames at the same time. The latter can result in screen tearing.) When people say that vertical sync makes a game look smoother, they don't mean that the edges are smoother, they mean that the game has less stutter or screen tearing.
For this issue, just play with the anti-aliasing settings, with Edge Smoothing both on and off within Sims 4's settings, and see what you get. And again, there may be limits to how much you can fix here, especially if you're zooming in enough that the placement of the individual pixels on your screen comes into play.
In general, when the Arc Control software says "X has to be disabled in application before modes can take effect," it means exactly that: in order for the Arc Control settings to apply, the corresponding settings within the game need to be disabled. So if you're enabling vertical sync in Arc Control, it has to be disabled within Sims 4's graphics settings. I'm not sure whether the same is true for anti-aliasing/edge smoothing, which is why I've suggested testing with in-game edge smoothing both on and off.