Windowed

1. Create a shortcut to Sims.exe
2. Right click that shortcut and go to properties
3. Append -w to the target box so the entire thing looks like "C:\Program Files (x86)\Maxis\The Sims\Sims.exe" -w
4. Click apply
5. Click ok
6. Run the shortcut

Make sure to also set the shortcut to run as administrator and run it in compatibility mode for Windows XP Service Pack 2 (not related to windowed mode but fixes other common problems). General Sims Recommendations

Borderless Fullscreen (Option #1)

1. Run the Widescreen Patcher and choose the DDrawCompat wrapper
2. Click Patch
3. Click Yes to Enable borderless fullscreen
4. Run game

Borderless Fullscreen (Option #2)

1. Create the shortcut with the steps from the Windowed section
2. Patch your Sims exe to something lower than your desktop resolution. For example, if your monitor resolution is 4k or 1440p, patch your exe to 1080p.
3. Download latest Magpie and extract it
4. Run The Sims from the shortcut you created (The Sims should be windowed)
5. Run Magpie
6. Change scaling mode to FSR
7. Change Capture Method to Desktop Duplication
8. Click in The Sims window so it continues playing
9. Press alt+F11 to enable borderless windowed with FSR upscaling