@Lightsims8 There's nothing wrong with a pre-built PC, and that's what you get if you don't build the computer yourself or order a (more expensive) custom build. Pre-built means exactly that: someone else has already built it for you. The important factor here is whether the builder uses standard components, like the ones you could buy on your own, or OEM parts that are only compatible with other OEM parts. And the difference here is not necessarily how long the system will last so much as how difficult it would be to upgrade or repair.
Having said that, the MSI is massive overkill for Sims 4 and not necessary, and its price is a bit high if Sims 4 is all it would run. That's not to say it's a bad option, exactly, only that you don't need to spend that much and won't get the full benefit of the better hardware. Sims 4 won't max out an RTX 3050 because of how the game is designed, and although faster hardware will lessen the severity of some of the lag and fps drops the game will produce, those performance issues will be present on any computer. So you'd be paying a lot more to see the same problems but with a lower impact.
Having 8 GB RAM rather than 16 would only help with performance if you were running other apps alongside Sims 4, or possibly if you had a very complicated save, but there's not much room between saves that use that much memory while still working and saves that are basically unplayable. I would go so far as to say that if you need 16 GB to run only your save and the EA App, your save is probably going to be impossible to run soon if not now. But again, this should not be a reason you avoid a PC that would otherwise be perfect, since you can add more memory so easily.
Windows 11 is not a problem for Sims 4 overall. Some people have problems with the upgrade process, or they install 11 on unsupported hardware, or they let OneDrive entangle itself, and then the game doesn't work anymore. But in general, if a computer will run Sims 4 in Windows 10, it'll run Sims 4 in 11 equally well. And you can always wipe the system and go back to 10 if you feel strongly about it.
If you do want something more powerful and are willing to spend the money, these two are good options:
https://www.bestbuy.ca/en-ca/product/cyberpowerpc-gamer-master-gaming-pc-amd-ryzen-5-5500-1tb-ssd-16gb-ram-geforce-rtx-4060-windows-11-en/17744732
https://www.bestbuy.ca/en-ca/product/skytech-nebula-gaming-pc-intel-core-i5-12400f-1tb-ssd-16gb-ram-geforce-rtx4060-windows-11-english/17459952
CyberpowerPC and Skytech use standard components for their builds. They're fairly well-known system integrators that offer custom builds and also sell prebuilt PCs with spare components, so you're getting the same kind of hardware you would if you ordered a custom PC. The second option has a better processor than the first, and Cyberpower had some issues with build quality in the recent past, but that seems to have been addressed, and purchasing from Best Buy offers additional protections.
Even cheaper are these two, although I don't know anything about the builders. Here again though, buying from a company with physical stores offers you good options if you run into trouble with the build; the components themselves should be as reliable as those from any other system integrator. The RTX 3060 ti in these builds is almost as fast as a 4060 and still massive overkill for Sims 4; you wouldn't see any practical difference in-game from one to the other.
https://www.canadacomputers.com/product_info.php?cPath=1446_1448&item_id=211036
https://www.canadacomputers.com/product_info.php?cPath=7_4527&item_id=254445
If you are comfortable with the builder, or at least that buying from Canada Computers is a good option, this one has an RTX 4060 and is cheaper than the Best Buy options:
https://www.canadacomputers.com/product_info.php?cPath=1446_1448&item_id=241405
All of these have processors that can more than keep up with the graphics cards, plus 16 GB RAM and enough storage, so you don't need to worry about those details. The question is how much overkill you want and how much you're willing to spend for it.