https://wccftech.com/galaxy-s21-will-use-bixbys-voice-recognition-to-unlock-the-device/

We are aware that the Galaxy S21 is going to go official in the coming months. As far as the unlocking options are concerned, you will get access to the under-display ultrasonic fingerprint sensor. In addition to that, you will also have access to the usual face unlock. However, based on a new report, the Galaxy S21 series can be unlocked using Bixby's voice recognition system.

According to the report, the Galaxy S21 will be the first device that will introduce the feature that will let the users use voice recognition to unlock their phone, which will be a Bixby feature. Technically, this feature will not be exclusive to the Galaxy S21 series only as sooner or later this will roll out to all devices that have the Bixby support, so you are good to go.