I don't know after which series exactly but at some point, the jagged shadows become an issue with Nvidia cards. Could have started after the 800 series. (
Possibly AMD as well but I don't remember.) I've experienced it with both a GTX 980 and now a GTX 1070. The fix can be done by editing the GraphicsRules.srg file. Steps taken may be different for a Mac user.
Find the file GraphicsRules.srg in this location C:/Program Files (x86)/Electronic Arts/the sims 4/game/bin
(This location may be different depending on where you have installed the base game.)
Make a copy of the original GraphicsRules.srg file just in case. (adding something like Orig or Backup at the end just so you know.) Keep that copy somewhere separate from the game folder.
Open GraphicsRules.srg with a text editor like Notepad
Press ctrl+f keys and a search window should appear. Type in prop $ConfigGroup ShadowMapSize 2048
and click Find Next.
Change the numbers 2048 to 3840 for 4k or 7680 for 8k.
Save the file and open the game to see the results. Make sure Lighting settings are set to Very High.
*You may notice the GPU working harder. I recommend starting off at 3840 before jumping to 7680. Even with having mine adjusted to 7680, it's still slightly jagged but much better.
