Caesar Cipher encoding process (customizable input and shifting) in Python
Some suggestions:


Pull out a function to shift a single character, and your top level code ends up being simply print(''.join([cipher(character) for character in input(…)]))
With an array containing the alphabet and a shifted array ("{}{}".format(alphabet[offset:], alphabet[:offset])) you can use str.translate to avoid any ord, chr, punctuation handling etc.
Use at least one linter like pycodestyle or flake8 to produce more idiomatic code.