@melissa369148 Your screenshots don't look that bad to me, but it's possible that they could look better, whether they used to or not. First of all, do you use GeForce Experience, and have you enabled the option to "optimize" your in-game graphics settings? If so, please disable that and test again.
If that's not the issue, did you ever mess with the Nvidia Control Panel settings, whether for Sims 4 or overall? I've seen a handful of complaints about antialiasing not working as it used to, but it's also true that the game's executable changed after the last patch (1.107). So if you did apply some settings to TS4_x64.exe, you'd need to reapply them to TS4_DX9_x64.exe for the DirectX 9 version of the game. (TS4_x64 now corresponds to the DX11 version.)
Additionally, you could play with the antialiasing settings just for fun and to see whether you can get an improvement. As long as you're choosing the "override application setting" option, the others should apply. If you go this route, test with the in-game Edge Smoothing option both enabled and disabled.
I will also say that some YouTubers likely play at higher resolutions, which would make their games look sharper than you'd see on a 1080p screen. So this may not be a valid comparison at all, depending on how the videos were recorded.
For the lag, there are so many possible causes, I couldn't list them all. But it's probably not related to the graphics, given how Sims 4 works overall and that there's no sign of the kind of serious graphical issue that would cause lag all by itself. If the lag you see is intermittent and not a huge problem, I'd chalk it up to how the game works. If it's interfering with your enjoyment of Sims 4 overall, I'd be happy to try to troubleshoot it with you. Let me know.