If you're trying to get raw bytes, you need to use

    print(b'\x80')

what's happening right now is that the '\x80' is treated as a unicode code point (see https://docs.python.org/3/howto/unicode.html#the-string-type), and when Python goes to print it, it gets encoded to the raw underlying bytes. Which, in the default encoding of utf-8 requires the extra byte.

>>> '\x80'.encode()
b'\xc2\x80'