Making a custom attribute unique

I created a new custom attribute for Okta user profile. Now I want to make this custom attribute unique.

This link in the documentation gives instructions of how I can do it.

But when I go to edit the custom attribute I never get a Restriction option as described in the documentation mentioned above. Can someone help me with figuring out how to do this?

This seems to be a part of User Types. Okta is in the process of rolling out changes for User Type however the features are still in Beta and may not be available.

I finally figured out that this is a feature that needs to be enabled for each tenant. If anyone comes across this question, please raise a support ticket asking to enable the feature.