Are updates available for Maps on the iPhone 6s plus
Apple does do updates but they're primarily server-side, so you might not notice the updates each time.

The best way to send Apple feedback about incorrect Maps data is to use Report a Problem under the ⓘ button.  There you can indicate what error the map has and send it to Apple.  Unfortunately, Apple has not published or otherwise indicated a timeframe as to when they will push-out corrections.