create procedure a (param1 date, cur_out out sys_refcursor) is
begin
...
end;

declare
    c number;
    col_cnt number;
    rec_tab dbms_sql.desc_tab;
begin
    c := dbms_sql.open_cursor;
    
    --is it possible to call our procedure that returns the cursor here?
    dbms_sql.parse(c, 'select ''x'' a from dual', dbms_sql.native); 
    
    dbms_sql.describe_columns(c, col_cnt, rec_tab);
    
    dbms_output.put_line(rec_tab(1).col_name);
    
    dbms_sql.close_cursor(c);
end;
/