CREATE TABLE LIKE another table but with additional columns

You can use the syntax below;

CREATE TABLE old_table_name (
  id serial,
  my_data text,
  primary key (id)
);

CREATE TABLE new_table_name ( 
  like old_table_name including all,
  new_col1 integer, 
  new_col2 text

);

The fiddle is here

No, there is no more succinct method of doing it. But ALTER TABLE can accept multiple arguments,

ALTER TABLE foo
  ADD column bar int,
  ADD column baz int;

Really if your goal is succinct, SQL is almost never an ideal language.

You can use the CREATE TABLE AS <query> option, as detailed in the documentation.

--Code not tested in PostgreSQL--

    CREATE TABLE MyNewTable
    AS
    SELECT *, CAST (NULL AS INT) AS IntCol1, CAST( NULL AS VARCHAR(10)) AS StrCol2...
    FROM MyOriginalTable 
     WITH NO DATA;