There was an extension but I think it came mere days before the deadline so manufacturers such as Tesla had already planned for it. AFAIK, all Teslas built for the US market since September 2020 have them.
I do have it as my car makes the back-up sound. I don't believe it does it going forward, however, although I haven't driven with the front windows open to check. My car actually came with Boombox at delivery (and heated wheel) which surprised me a bit. Have had fun with the horn 'fart' sound. Neighborhood kids like it.... Just got first update today (2021.4.12).