oracle SQL to evaluate string having expression

select level from dual connect by level<=5;

select listagg(level,'*') within group (order by level) from dual connect by level<=5; 

select xmlquery(listagg(level,'*') within group (order by level) returning content) from dual connect by level<=5; 

select xmlquery(listagg(level,'*') within group (order by level) returning content).getnumberval()  xml_val from dual connect by level<=5;