Silence Unknown Callers on Apple Watch SE

Hi there,

I recently purchased two Apple Watch SE's for my two kids as stand alone devices (no phones required for setup), I recently came over from the Verizon Gizmo watches. Currently, there is no feature available for them to silence unknown callers. These numbers are brand new to us but have already received spam calls, and as much as I reinforce with them not to answer unknown numbers, I would like to have the ability to silence unknown callers and send them to voicemail exactly like my iPhone currently does.

Is there a way to activate this feature? I do not see it in the Watch app on my phone (where I manage their devices) and it is not in the Phone app on their watches.

Any help is appreciated!