Apple Watch series 3 - can't update to watch os 6
My Apple Watch series 3 has been updated to watch os 5.3.2.
How can I update it to watch os 6.0?
It is paired with an iPhone XS running latest ios 13.1.2.
According to this article [https://support.apple.com/en-us/HT204641] update should be visible in Watch app on an iPhone but it's not. Can anyone help?
Cheers!
Apple Watch