Locating a schema that owns a role
Roles are not owned, but granted to users:

select grantee from dba_role_privs where granted_role = 'LANDING_R';


Object privileges granted to LANDING_R:

select * from dba_tab_privs where grantee = 'LANDING_R';


System privileges granted to the LANDING_R:

select * from dba_sys_privs where grantee = 'LANDING_R';