The LEGO Bugatti Chiron Speed Champions Race is near Brickchester Airport. You will be racing head-to-head against a Bugatti 2018 Chiron. Set the difficulty to Easy and use rewind if you make a mistake and you should have no trouble beating it. This will unlock the LEGO Speed Champions 2019 Bugatti Chiron if you haven't got it already.
I had completed this before the title update was released, but unlike all the other achievements that unlocked after loading up the game, I had to win the LEGO Bugatti Chiron Speed Champions Race a second time. Although this time I was able to use a fully upgraded LEGO Speed Champions 2019 Bugatti Chiron.