@MinVediva If you're not looking for the best computer $1,500 can buy, you really don't need to pay nearly that much, even with the monitor included, for Sims 4. There are a few rough categories to choose from even below $1,000, and the question is at what point does price become more important than performance.
If your only goal is to play Sims 4 on ultra settings without the game lagging too much (it'll lag for sure, that can't be avoided, but it won't be the hardware's fault), then these are as low as I would go. Performance should be smooth, other than when the game inevitably lags, and you'll have room for whatever else you want to install. The second one has a newer and better processor, which should help with longevity and with some of the Sims 4 lag, but it's not strictly necessary.
https://www.amazon.com/Skytech-Chronos-Mini-Gaming-Desktop/dp/B09R1V8X6F
https://www.bestbuy.com/site/skytech-gaming-chronos-mini-gaming-desktop-intel-core-i3-12100f-16gb-memory-nvidia-geforce-gtx-1650-500gb-nvme-ssd-black/6537309.p?skuId=6537309
The next tier means smoother graphics, especially if you get a monitor with a higher refresh rate (more on that below), and more of a buffer to absorb the effects of the game lagging. To be clear, this is about the game tripping all over itself, not the hardware, but faster hardware can resolve those tie-ups marginally more quickly. The faster graphics card also leaves some room for Sims 4 to get more demanding, if it does, or for the eventual Sims 5 to be more graphics-intensive than that. Given the small difference in price between this and the next tier up, this is the only computer I found that's worth the price given its hardware.
https://www.bestbuy.com/site/skytech-gaming-nebula-gaming-desktop-intel-core-i5-12400f-16gb-memory-nvidia-geforce-rtx-3050-500gb-nvme-ssd-black/6537311.p?skuId=6537311
Finally, these computers are overkill for Sims 4 and almost certainly always will be, but since these systems are only around $900, they're worth mentioning too. Aside from the faster graphics card, you're also getting twice the storage for the first two, which is convenient if not necessary for Sims 4 and schoolwork.
https://www.newegg.com/skytech-st-azure-0641-b-ne/p/3D5-000Z-000Z2
https://www.newegg.com/ibuypower-slatehakoi5n3601/p/N82E16883993002
https://www.amazon.com/Skytech-Blaze-3-0-Gaming-Desktop/dp/B0B52VH28X
https://www.amazon.com/Skytech-Azure-Gaming-PC-Desktop/dp/B0BRBR8C9Y
Within a given tier, the hardware isn't meaningfully different other than the extra storage of the first two $900 options. But storage is very easy to upgrade and quite cheap these days, so you wouldn't be locking yourself into 500 GB with the other options. All of these have 16 GB RAM, which is convenient for multitasking and will probably be necessary eventually even if it's not right now.
I chose desktops from companies with a reputation for good build quality and getting the most out of their hardware. You might see a slightly cheaper option with the same hardware from HP or Acer, but I would suggest avoiding those given your budget can accommodate a slightly higher price. Some manufacturers use proprietary components that don't work as well and are not interchangeable with commonly-available parts, so repairs and upgrades can be much more difficult.
For monitors, the single most important feature is an IPS panel (as opposed to VA or TN), which has the highest-quality colors and widest viewing angles. Second, for many of us at least, is a higher refresh rate. Many people can readily distinguish between 60 or 75 Hz and 120 or higher, especially at younger ages, with the higher refresh rates making everything from games to dragging a desktop window feel smoother and more responsive. Even some of those who can't tell the difference, consciously at least, report a subjective improvement.
However, if you're going for one of the computers in the first tier, you may not get a lot of benefit from a refresh rate higher than 75 Hz. The 1650 would run Sims 4 a little faster than that most of the time and sometimes drop below it, so something like one of these would be fine. I realize that I'm listing a lot of options, but aesthetics matter to a lot of people, so you might cross off half of them because you don't like the stand or something.
https://www.amazon.com/VA229HR-Monitor-Frameless-1080P-Viewing/dp/B07WMTJGFX
(same as above; you could probably get Best Buy to price match)
https://www.bestbuy.com/site/asus-21-5-ips-led-fhd-monitor-black/6401041.p?skuId=6401041
https://www.bhphotovideo.com/c/product/1457452-REG/lg_22mk430h_b_22_full_hd_ips.html
https://www.bhphotovideo.com/c/product/1299685-REG/lg_24mb35v_w_23_8_led_lcd.html
https://www.amazon.com/ASUS-23-8-1080P-Monitor-VA247HE/dp/B09DHNBDGD
https://www.bestbuy.com/site/samsung-t350-series-24-ips-led-fhd-freesync-hdmi-vga-dark-blue-gray/6420870.p?skuId=6420870
https://www.amazon.com/MSI-Pro-MP243-Certified-Protection/dp/B0B94NQ1YC
https://www.amazon.com/ASUS-VA24EHE-Monitor-1920x1080-D-Sub/dp/B07Z8TC28F
(again, same as above)
https://www.bestbuy.com/site/asus-va24ehe-23-8-full-hd-led-lcd-monitor-169/6419208.p?skuId=6419208
If you're getting a computer with an RTX 3050 or especially a 3060 for a graphics card, then it's well worth the upgrade to 120 Hz or higher. Sims 4 should run at 1920x1080 at or above 144 fps under ideal conditions on a 3060, and lower but still well over 100 on a 3050. Some situations will create fps drops, that happens on even much more powerful systems, but most of the time you'd see closer to 144. Even with a 1650, the price premium for a higher-refresh-rate monitors is low enough to be worth considering for general use.
https://www.amazon.com/LG-24GN600-B-Ultragear-Virtually-Borderless/dp/B08PHKNNRY
https://amazon.com/MSI-Refresh-Monitor-Optix-G242PM/dp/B09X32W7F9
https://www.amazon.com/Lenovo-G24-20-FreeSync-Certified-Adjustable/dp/B0B94RK4BK
https://www.newegg.com/metallic-black-msi-optix-g2412-24/p/N82E16824475257
https://www.bhphotovideo.com/c/product/1703068-REG/gigabyte_g24f_2_us_24.html
https://www.bhphotovideo.com/c/product/1727984-REG/msi_g2412_24_full_hd_170hz.html
https://www.bestbuy.com/site/asus-tuf-23-8-fhd-165hz-1ms-freesync-premium-gaming-monitor-displayporthdmi/6501810.p?skuId=6501810
In terms of specs, there aren't many meaningful differences, although look for a peak brighness, measured in nits, at or above 300 if you like a brighter monitor. If you don't like a particular brand's monitors in general, that's also a good distinction to make. For example, I'd never buy myself a Dell monitor even though they're high quality overall just because I don't like the way the screens look.
If you have more questions about any of this, please feel free to ask.