Google Camera v5.3 app which is included in Android P Developer Preview 4 (aka beta 3) does not exactly bring any new changes to the table, but it does point to some upcoming features, though. According to a recent APK teardown, Google may soon include RAW support to the Google Camera app. In addition to that, corrections for wide-angle distortion will also become available, probably, and the same can be said for multi-channel audio.
About two years ago, a Google Camera app teardown suggested that RAW support may be coming to the app, but that never happened. Now, we have similar hints that it may happen, and hopefully, this time, it will, though we cannot say for sure. RAW support is available in a modified version of Google Camera app, though, but that doesn't count, as it's not an official release. Now, as already mentioned, corrections for wide-angle distortion may be coming as well, and that is actually a problem that many of you probably never noticed. This problem occurs if you frame your shots so that people are placed on the edges of your photo, the lens may distort them due to a wide-angle lens. You can fix this via a photo editing software, like Adobe Lightroom, for example, to a degree, at least, but it would be nice to avoid this problem altogether.
Last, but not least, multi-channel audio may be on its way. 'IMAX_AUDIO' and 'MICROPHONE' are mentioned in the Google Camera v5.3 code, and in combination with some other info, this could point to a multi-channel audio. This is not a confirmation of any sort, though, so don't keep your hopes up, this feature may take some time to implement, if it ever arrives. That is more or less it, as already mentioned, Google Camera v5.3 app is available on Android P Beta 3 build, and there's no point in installing that APK on any other phone as it will not work on devices that do not run a specific version of Android P, in case you were wondering.