You have two (or possibly three) choices.
Aspyr provide a Sims 2 Extras download, if you register with them, which includes BodyShop and the Package Installer. I've not used the package installer, but presume it has all the disadvantages of the EA/Maxis supplied original one, with nonsensical filenames and no ability to inspect what is actually being unpacked and be selective about it. You can find that here:
https://www.aspyr.com/games/the-sim...ckage-installer
There's also jfade's MacUnPac. It requires Java in order to run, which can be fiddly to get installed on a modern Mac, and there are reports that sometimes it only shows a blank window. It's also unsupported at this point, unfortunately. But it's the closest thing Mac users have to the Clean Installer. You can find that here:
http://sims.jfade.com/index.php?category=1&subcat=5
Personally I push any Sims2Pack files across to my old Bootcamp partition, open them there in Clean Installer, and then copy them back to my game on macOS, but that's only really an option if you have a copy of Windows, and either VM software or a Bootcamp setup.