Many of the older Sims titles have never been available on Origin or if they were, they are no longer supported. The only way to play these games are from CD/DVD copies (on the Windows OS) and will require an external CD drive if your computer does not have one. You can certainly find copies of these games in game stores that sell used games, Amazon, E-Bay or Goodwill/Salvation Army stores. Even if the game is used you can still use the game codes since EA no longer requires the codes to be registered to play.
If you play on a Mac, Aspyr has ported and updated some of the older games to run on Catalina as 64 bit games and they are available for purchase on the Apple App Store.