watchOS 3.2.3 can be downloaded through the dedicated Apple Watch app on the iPhone by going to General --> Software Update. To install the update, the Apple Watch must have 50 percent battery, it must be placed on the charger, and it must be in range of the iPhone.
An iPhone running iOS 10 or later is required to download the new software, but it is available for all Apple Watch models.
During the beta testing period for watchOS 3.2.3, no major changes or new outward-facing features were discovered, so watchOS 3.2.3, like watchOS 3.2.2 appears to focus mainly on performance improvements and bug fixes.
watchOS 3 will soon be succeeded by a new version of watchOS, watchOS 4, which was introduced at the June Worldwide Developers Conference.