amspectrum I would expect this hardware to be able to run Sims 4 on at least high-ultra graphics settings before you factor in high poly custom content. You might be able to get away with ultra, depending on which packs you have installed and how smooth you want gameplay to be. The 680M tha comes with the 7735U is clearly a better choice, but if the price is higher than you'd like, the 660M is still good enough for high-ultra settings before factoring in cc.
Your high poly cc will of course increase the demands the game places on your hardware, but it's often the sheer amount of cc that's on the screen at once. So if, for example, you have a few hairs you love, but your sim will only wear one at a time, that's going to make less of a difference than if the sim is wearing a high poly hair and top and shoes and you also have a high poly couch in the living room. Still, this hardware should allow you to play on at least high graphics settings even with a reasonable amount of cc, like, say, not an entire 60x60 lot stuffed with cc items.
The the one small concern I have about this laptop is the 1x16 GB RAM configuration. 2x8 GB would be better from a performance standpoint, although this only makes a difference for certain kinds of tasks. I'm not actually sure how much of a difference it would make to Sims 4: I believe some, but it's hard to quantify. So if you can find a 2x8 GB option, get that instead.
If you're curious about the concept in general, look up dual-channel vs. single-channel RAM.