Apps can choose [1] to tie have keys to the current set of enrolled biometric credentials (i.e. faces or fingers), and at least my password manager does that, as far as I remember from some testing.

Some apps don't, and some even react really poorly to a change of the biometric set (i.e. crashing at every Face ID use with no way to reset other than reinstalling), so I'm also not too keen on testing this on my main device.

One thing that surprised me during my limited testing was that Apple apparently doesn't make use of this capability for storing the "encrypted notes" passphrase, which effectively also reduces the security of that to that of the device passcode.

[1] https://developer.apple.com/documentation/security/secaccess...