Query to check the granted roles to a user

SELECT * 
 FROM DBA_ROLE_PRIVS 
 WHERE GRANTEE = '&USER';

Query to check privileges granted to a user

SELECT * 
 FROM DBA_TAB_PRIVS 
 WHERE GRANTEE = 'USER';

Privileges granted to a role which is granted to a user

SELECT * FROM DBA_TAB_PRIVS WHERE GRANTEE IN 
(SELECT granted_role FROM DBA_ROLE_PRIVS WHERE GRANTEE = '&USER') order by 3;

Query to check if user is having system privileges

SELECT * 
 FROM DBA_SYS_PRIVS 
 WHERE GRANTEE = '&USER';

Query to check permissions granted to a role

select * from ROLE_ROLE_PRIVS where ROLE = '&ROLE_NAME';
select * from ROLE_TAB_PRIVS where ROLE = '&ROLE_NAME';
select * from ROLE_SYS_PRIVS where ROLE = '&ROLE_NAME';