Yes it is still available. I am on a Mac so I am assuming that Origin displays the same. On my computer, if I go to Store/Browse Games/The Sims it is listed in a drop down menu below the Sims 4 games. When you choose The Sims, there is a further sub-menu just for Sims 4, don't click that. Just stick with the top The Sims menu and you will find it and all the expansions listed on the bottom of the list. I don't have Steam but I am pretty sure it is available on it too.
https://lh3.googleusercontent.com/pw/ACtC-3dwTbFIhkRvRq-TMquoGW5v0li1CgZA--94jpvokUJNFYuw3yY0w2FIdFjhMBVYy1d3fU9CzJMgxb7VUI2WepSOPUpNrlqiJ8vwmqMFdbVYzrYTb_oQ6ygbHnoCTb-DB4DYxzZHrumJzqt2IP1hP383fA=w1000-h904-no?authuser=0
https://lh3.googleusercontent.com/pw/ACtC-3c1EjUBUFElUt_pGrFqR5kGSO6S73J71Byny574ONiF7z_MoACLMB_F7U2nu4LnknAh-ZNfBklOoSH6KHLydZg_upgGiveG9V4VNvVWn5bd92Wnrpn9QFBd3V_XDTpVlkyqCMGOb7S35QyvRVk3_o4r5w=w819-h1000-no?authuser=0
You may already have it though. If you registered your disk copy, you would be entitled to a download.
