Microsoft is adding next-gen controller features for older Xbox controllers, but only for some Xbox Insiders. This was announced in a blog post, stating the new firmware will allow older Xbox controllers to use features that were only previously used on the Xbox Series X|S controllers.
The firmware update applies to Xbox One controllers with Bluetooth Support, Xbox Elite Wireless Controller Series 2, and Xbox Adaptive Controllers. Generally, it adds better cross-device Bluetooth connectivity and reduced latency. The cross-device Bluetooth connectivity uses Bluetooth Low energy, allowing for better connections to PCs, iOS, and Android devices (that support it of course). The controller can also remember one Bluetooth device and one Xbox console, which allows people to switch between the two devices by double-tapping the sync button.
The listed controllers are also getting Dynamic Latency Input support on Xbox Series X|S. This technology delivers controller inputs to the console more effectively, reducing latency while playing. Both of these features are already available in Xbox Series X|S controllers. This update is available for Alpha Skip-Ahead and Alpha members of the Xbox Insider Program.