Can you play two different versions of sims 4 on one pc?

Go to Game Library then Game Properties, or whatever the equivalent is in your app (I'm using Origin on Mac).
Open the Advanced Launch Options tab.
https://i.postimg.cc/vHmGyJ4Y/Screen-Shot-2023-02-11-at-4-15-33-PM.png

Enter "-disablepacks:" followed by the codes of all the packs you want to disable, with commas in between, no spaces.
For basegame you need to disable them all, like so

-disablepacks:EP01,EP02,EP03,EP04,EP05,EP06,EP07,EP08,EP09,EP10,EP11,EP12,GP01,GP02,GP03,GP04,GP05,GP06,GP07,GP08,GP09,GP10,GP11,GP12,SP01,SP02,SP03,SP04,SP05,SP06,SP07,SP08,SP09,SP10,SP11,SP12,SP13,SP14,SP15,SP16,SP17,SP18,SP20,SP21,SP22,SP23,SP24,SP25,SP26,SP28,SP29,SP30,SP31,SP32,SP33,SP34,SP35,SP36,SP37,SP38,SP39

https://i.postimg.cc/CxBYBbC9/Screen-Shot-2023-02-11-at-4-15-45-PM.png

Click Save on the launch options tab.

Then when you open your game and go to Load Game, you'll see these flags next to saves that used packs you have disabled.
https://i.postimg.cc/FHMvj1Dz/Screen-Shot-2023-02-11-at-4-16-38-PM.png

If you don't load those saves, they will remain undisturbed. Might be a good idea to make a backup just in case you mis-click one day, though.
If you create a new game, you'll have the basegame-only experience.

Anytime you want to play with one or more packs enabled again, change the advanced launch options code accordingly.