Oracle 23c

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select * from dual


DUMMY


X


declare
  v_column_name all_tab_columns.column_name%type := 'DUMMY';
begin
  for r_row in (select v_column_name as col from dual)
  loop
    dbms_output.put_line(r_row.col);
  end loop;
end;
/
1 rows affected

dbms_output:
DUMMY

declare
  v_column_name all_tab_columns.column_name%type := 'DUMMY';
  v_cursor sys_refcursor;
  v_value varchar2(4000);
begin
  open v_cursor for 'select "' || v_column_name || '" from dual';
  loop
    fetch v_cursor into v_value;
    exit when v_cursor%notfound;
    dbms_output.put_line(v_value);
  end loop;
end;
/
1 rows affected

dbms_output:
X