Apple has seeded the sixth developer beta update to watchOS 5.3, just after a week of its fifth update. The changes are not known as of now, but mostly would be bug fixes to polish the OS before the major update of watchOS 6.
The update be downloaded from the Apple Developer Center by those taking part in the testing program. To install the update, the Apple Watch needs to have at least 50 percent battery, it must be placed on the charger, and it has to be in range of the iPhone.
Build six for watchOS 5.3 is number 16U5569a, up from the fifth build 16U5566a. The update may have brought some hidden features in order to support the Apple Card. Apple also released the seventh beta for iOS 12.4 along with this update.