As a general rule, upgrading between minor versions (e.g. 6.x to 6.y, where x < y) can be done by simply installing the new release and restarting the Beat process, because the Beats keep backwards compatibility when it comes to configuration and exported fields. Please review the release notes for potential exceptions.
Upgrading between non-consecutive major versions (e.g. 1.x to 6.x) is not supported. If you are on version 1.x of the Beats, we recommend first upgrading to 5.6.