three arguments you need to know for this are padding, truncation and max_length.
padding controls the padding. It can be a boolean or a string which should be:
True or 'longest' to pad to the longest sequence in the batch (doing no padding if you only provide
    a single sequence).
'max_length' to pad to a length specified by the max_length argument or the maximum length accepted
    by the model if no max_length is provided (max_length=None). If you only provide a single sequence,
    padding will still be applied to it.
False or 'do_not_pad' to not pad the sequences. As we have seen before, this is the default
    behavior.
truncation controls the truncation. It can be a boolean or a string which should be:
True or 'longest_first' truncate to a maximum length specified by the max_length argument or
