Using SESSION_ROLES it will retrieve the current roles that are active for a user in a session.

Example:
SQL> connect test/…
SQL> select * from session_roles;

ROLE
——————————
DELETE_CATALOG_ROLE

Using “SET ROLE” one can change the roles active in the current session.
Example:
SQL> select * from session_roles;
ROLE
——————————
TEST11

Enable specific set of roles in the current session
SQL> set role test11, delete_catalog_role;
Role set.

SQL> select * from session_roles;
ROLE
——————————
DELETE_CATALOG_ROLE
TEST11

Enable all roles in the current session
SQL> set role all;
Role set.