Samsung is seemingly planning on offering Bixby Voice as a biometric unlock method on the Galaxy S21 series. The device is expected to launch with One UI 3.1 out of the box, which should have this feature.
As SamMobile notes, Bixby previously had the ability to set a voice password for hands-free device unlocking which Samsung removed eventually. Now, with One UI 3.1 on the Galaxy S21 series, Samsung will bring back a similar feature that will allow users to unlock their device via their voice. It is possible that Samsung will include highly sensitive mics on the Galaxy S21 series to ensure the feature works properly.
While voice unlock might sound cool on paper, it is unlikely to be the most secure biometric unlock method around. Samsung already offers face unlock on its existing devices but it is not as secure as the fingerprint scanner since it only relies on the front camera and not any depth camera like iPhones. The company previously offered an iris scanner on its flagship devices which was far more secure but removed it in a bid to achieve a bezel-less look on its newer flagships.
Samsung is expected to announce the Galaxy S21 series in mid-January to counter the iPhone 12 series from Apple.