Oracle: V$SES_OPTIMIZER_ENV, V$SYS_OPTIMIZER_ENV, V$SQL_OPTIMIZER_ENV

select
   name,
   value,
   isdefault,
   sql_feature
from
   v$ses_optimizer_env
where
   sid = sys_context('userenv', 'sid')
order by
   lower(replace(name, '_'));

select * from v$sys_optimizer_env;  

select * from v$sql_optimizer_env;