Oracle 18c

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create type my_sdo_geom_type as object ( 
  shape sdo_geometry, 
  member function GetOrdinates(SELF in my_sdo_geom_type) 
  return mdsys.sdo_ordinate_array deterministic) 
/ 
create or replace type body my_sdo_geom_type as 
  member function GetOrdinates(self in my_sdo_geom_type) 
  return mdsys.sdo_ordinate_array is 
    begin 
       return shape.sdo_ordinates; 
    end; 
end; 
/ 
create table lines (my_sdo_geom_col my_sdo_geom_type);
insert into lines (my_sdo_geom_col) 
  values (my_sdo_geom_type(sdo_geometry('linestring(10 20, 30 40, 50 60)')));
1 rows affected

select
  (my_sdo_geom_col).GetOrdinates()
from
  lines
--The previous query returned an emptry resultset because db<>fiddle doesn't know how
--  to interperet varrays. So I'll extract the varray elements as text using
--  the technique in this post: "Get varray values as concatenated text list"
--  https://stackoverflow.com/a/72683824/5576771
select s.my_array_str
from   lines l
      CROSS JOIN LATERAL (
         SELECT LISTAGG(column_value, ',') WITHIN GROUP (ORDER BY ROWNUM)
                  AS my_array_str
         FROM   TABLE(l.my_sdo_geom_col.GetOrdinates())
      ) s


MY_ARRAY_STR


10,20,30,40,50,60