There are dozens of cases that were designed for the Amazon Kindle Oasis 2 by companies such as Casebot and Ayotu, that do not work on the latest generation Oasis 3. This is because the Oasis 3 has their magnets in a slightly different position, the second gen model had their magnets on the back contoured edge. This means that most Amazon cases for the Oasis 2 and various 3rd party ones do not have the sleep and wake function.
Amazon has not made official cases yet for the Amazon Kindle Oasis 3. This means that there are no official products with the sleep and wake functionality that were exclusively designed for the 10th gen e-reader. There is a leather case with a magnetic attachment that works on the 9th and 10th gen and users have stated that the sleep and wake functionality actually work. This is the same product found in the Kindle Oasis Essentials Bundle. The lionshare of sleep and wake cases and covers are only geared towards the Paperwhite 4 and entry level Kindle basic.
Many of the 3rd party vendors have stated their sleep covers work with the 10th gen Oasis, in the description of their products, but that is simply not the case, no pun intended.
Michael Kozlowski is the Editor in Chief of Good e-Reader. He has been writing about audiobooks and e-readers for the past ten years. His articles have been picked up by major and local news sources and websites such as the CBC, CNET, Engadget, Huffington Post and the New York Times.