Does postgres support custom attributes on users/roles?

Question

Is it possible in Postgres v14 to add custom attributes to a user account and reference those in a RLS policy?

For instance, suppose we have tenants and I wanted to define fred with the custom attribute (tenant_id = 123) and bob with (tenant_id = 987).

Is this possible? If it is, can these then be referenced in a RLS policy on a table?