@rosbe17 The crash reports Sims 3 generates aren't particularly helpful. The ones macOS generates aren't either—they say the game crashed with an access violation, which is true, but that's too generic of an error to be of any use.
Please try playing with all the graphics settings down to the minimum, and Advanced Rendering disabled, and Object Hiding enabled. You may not need to play like this going forward, but it's a useful test. When you change the graphics settings, do so at the Main Menu, then quit to desktop before loading a save.
Also make sure your Mac can properly cool itself, which means playing on a hard flat surface (like a desk) or using a laptop tray or cooling pad. Don't let it rest on a blanket or your clothing.
If none of this helps, please create a new admin account on your Mac and try all the above there as well. You won't have access to your saves or other user data, but the game itself should still be playable.