The SPACE function returns as many empy strings as the number specified. The return value is a VARCHAR type.
SPACE(N)
SELECT SPACE(8);
space(8)
======================
' '
SELECT LENGTH(space(1048576));
char_length( space(1048576))
===============================
1048576
SELECT LENGTH(space(1048577));
char_length( space(1048577))
===============================
NULL
-- string_max_size_bytes=33554432
SELECT LENGTH(space('33554432'));
char_length( space('33554432'))
==================================
33554432
SELECT SPACE('aaa');
ERROR: Cannot coerce value of domain "character" to domain "bigint".