At a minimum you should buy a laptop with an Intel HD i3-7100u with the integrated intel HD 620 graphics core. It can play the Sims 4 pretty well at 1366x768 as shown in the following video. However, installing expansions can lower performance if they make the game more graphically demanding.
https
/www.youtube.com/watch?v=8zO0-GvekQw
If you can afford a laptop with a nVidia 940mx, then buy it. It can play The Sims 4 at 1080p and high settings with decent performance. The 940mx is a budget dedicated graphics card which can come with a laptop selling for as low as $550... at least in the US...