One of the features we’re waiting for is the new Bluetooth volume memory feature. This was first spotted on the Android Open Source Project (AOSP) before the release of Android P Developer Preview 2 (Beta 1). The main function of this feature was to keep the track record of the volume setup for every Bluetooth devices.
Basically, it’ll remember what volume level you set each of your devices to before you disconnected from them. This will ease the volume setup with every connection.
As per the update, this feature works on Google Pixel devices and on the Essential Phone. Both of the smartphones is the one who got the new Android 9.0 P update. If you wish to get the similar feature on your device, you can get an app named Bluetooth Volume Control which works on almost every Android device with version 4.4 above.
Download – Bluetooth Volume Control
Source – XDA Developers