WITH 
  L(ID, VAL_L) AS (VALUES (1, '1'), (2, '2'))
, R(ID, VAL_R) AS (VALUES (1, '11'))
SELECT L.ID, L.VAL_L, R.VAL_R
FROM L
LEFT JOIN LATERAL
(
SELECT *
FROM R
WHERE R.ID = L.ID
) R ON 1=1;

|ID         |VAL_L|VAL_R|
|-----------|-----|-----|
|1          |1    |11   |
|2          |2    |     |