Some release notes are generic - and apply to both iOS and iPadOS platforms. While iOS and iPadOS are closely related, some features will not be applicable to both OS platforms.
To reiterate, the Standby function is currently only available to iPhone.
Apple invite submission of comments and feature requests via its Product Feedback portal. If you would like to see a specific feature or functionality in a future version of iPadOS, this would be the most appropriate channel through which to make a request:
Feedback - iPad - Apple