Is there any way to enforce challenge?

Good Morning,
I would like to enforce Cloudflare to display “challenge” to some dynamically typed users (by our algorithm) or at least to update Access Rules in order to deny that users accessing to the app.

Is there any chance to achieve that?
I can not find method to do above in api documentation.

Best Regards!

I am not an API hero but I doubt this can be achieved by adding firewall rules. But you need to identify the users with their IPs.

Yes, I can already achieve that.

All I want to do is to notify Cloudflare, that we have user which should be checked if is not a robot, or (if this scenario is impossible) to blacklist him (by sending specific request to CF endpoint or (un)setting specific HTTP header).