Sequence-to-sequence models with attention are known to be limited by a maximum sequence length. So how can we handle sequences of arbitrarily large size? Do we just set a very large maximum sequence length?
You simply split the sequence into smaller sequences; while there are some long-distance dependencies in language, that is generally not a problem for this.
A sentence would typically be short enough, and very long sentences are composed of shorter clauses which would form independent units (albeit connected with each other).