With Catalina and Big Sur when you are booting while using keyboard options like ⌥, ⌥R, or ⌘⌥R holding the keys down until you see the Apple logo is not enough, you must continue holding the keys down until you see a progress bar.
Here's what Apple has to say about it in part:
On Mac computers that play a startup sound, you can release the keys after the second startup sound.
On Mac computers that have the Apple T2 Security Chip, you can release the keys after the Apple logo appears and disappears for the second time
