HELP! Sims 4 Constantly Crashing!!

melagigante  Please test again after yesterday's patch, just to see whether it makes any difference.

In general, you should be able to run Sims 4 on ultra settings at 1920x1080.  If you can't, that means something else is wrong, although what exactly that is could be difficult to figure out.

The next step here would be to use a hardware monitoring app to see whether your CPU or GPU is overheating, especially given the age of the system.  I like hwinfo, which lists a LOT of data, but you can ignore most of it for now and focus on only the temperature readings.  Open it before you start playing Sims 4, choose Sensors Only, and check on it when you're done playing (or when the game crashes).  Let me know how hot the CPU and GPU cores get: they shouldn't be above around 90º and 75º, respectively, although a bit more is okay if the temps are stable.

Lowering the in-game settings reduces the load on your hardware, of course, but only if the hardware can't generate higher framerates to compensate.  Sims 4 has a cap of 200 fps, so if you were getting, say, 80 fps on ultra, you might get 120 fps on high (just an example, not actual data) with the hardware working just as hard as before.  That's why it sometimes only helps to lower settings drastically.