Pc build for sims 4,please help!

@xws3qax4wier  I don't get overwhelmed by hardware questions, so feel free to list whatever's on your mind.  Who knows, we might even find out whether this site has a per-post character limit.  (Let's hope we don't find out.)

1)  You could absolutely upgrade the graphics card if you wanted.  A 5700X will also keep up with everything currently on the market under $1,000, and maybe some of the more expensive ones.  (I can check benchmarks if you'd like, but you get the idea.)  However, if the price of upgrading is relatively high, I'd consider waiting: a GPU that costs $800 today might only be as fast as a $300 model in three years, so you could put away the extra money and get something faster if and when you need it.

2)  Sims 4 can't properly use even 16 GB memory.  Its practical max seems to be in the 6-8 GB range; above that, the save runs poorly on any system.  This is a limitation of the game engine, not the hardware.  The only time RAM spikes above that is when the save or the game itself has a bug, for example the Father Winter issue from a couple years ago.  So no, you won't see any benefit from installing more than 32 GB over the entire life of Sims 4.

This is also completely or almost completely independent of the resolution you're using: more pixels means more VRAM used, but the GPUs you're considering have far more memory than Sims 4 can utilize.  The last time I checked my own game, my GPU topped out at about 2.5 GB VRAM used while running on ultra settings at 2560x1440 and around 170 fps.

Speaking of fps, it's not really your question, but my overclocked RTX 2070 can maintain a stable 169 fps (ultra settings, 2560x1440) under ideal conditions, and its core load isn't close to maxed out.  In fact, the GPU isn't even running at its turbo speed a lot of the time.  I do see fps drops, even as low as the 90s here and there, in certain worlds and during inclement weather, but even then, the core load is somewhere in the range of 60%.  (The CPU, RAM, and SSD aren't anywhere near maxed out either, and temps are fine across the board.)  So this looks pretty clearly to be a limitation of the game engine, not my hardware.

The number of sims in a save can significantly impact fps because the game engine has more to process, but this has nothing to do with the graphics card.  The CPU does matter here, but the ones you're considering are fast enough that the game engine will be the limiting factor.  What can impact GPU load is having more sims on the active lot, especially if they're wearing high poly custom content, but here again, the cards you're considering are more capable than the game engine and wouldn't themselves limit the performance.

I mention this because I have my doubts about the website you're looking at, but also because I want you to have reasonable expectations here.  I'm not sure there's any way to overcome Sims 4's limitations, and above a certain point, faster components aren't going to make any difference.  That doesn't mean there's no point in spending more money—in particular, a strong processor is a great investment when it enables you to install a faster GPU down the line.  It's just that Sims 4 is limited in what it can reasonably handle regardless of the computer running it.