Dumb question from a newbie about Sims 1

Hi - I am really excited at the prospect of the re-releases having played a little bit of Sims 1 when I was young, but I never played the expansion packs and haven't played any Sims games since. My question which I can't seem to find a clear answer for on Google is how the expansion packs work in terms of items e.g. if you install the Superstar pack, can you then buy objects that are exclusive to the packs in buy mode for your home in the base game? Is that even how it works? Thanks for any advice on this as I remember the number of items was quite limited in the base game.