sqlite alter table add MULTIPLE columns in a single statement

No, you have to add them one at a time. See the syntax diagram at the top of SQLite's ALTER TABLE documentation:

There's no loop in the ADD branch so no repetition is allowed.

The only thing so far possible that I use is

BEGIN TRANSACTION;
ALTER TABLE tblName ADD ColumnNameA TEXT DEFAULT '';
ALTER TABLE tblName ADD ColumnNameB TEXT DEFAULT '';
ALTER TABLE tblName ADD ColumnNameC TEXT DEFAULT '';
COMMIT

Note that there are ; on purpose to make the query be read as multiple lines.

Then I run this query and get multiple columns added in on run... So no not in one line, but yes in one query its possible.