Flagship iPhones have been unlockable through Face ID only since 2017. Now, however, there are hints that Apple might bring its only real alternative, Touch ID, back in 2021. It will apparently be an in-display version for the first time, with the company leaving the Home button in the dust with the putative new technology.
https://www.notebookcheck.net/Apple-might-launch-in-display-Touch-ID-with-the-2021-iPhones.518019.0.html