UPDATE (June 8th, 2021):

The much-awaited Apple Music support for lossless and Spatial Audio music tracks is finally here. It was announced last month but is now getting rolled out via a server-side change. If the feature is compatible and available for your iPhone, you should be able to see a new "Dolby Atmos" option by visiting Settings -> Music. It should be noted that there is a possibility that you might not see the button straightaway as the feature has not reached everyone yet.

As for the Lossless audio, you should see a new toggle with the same name in the settings. It should be turned on if you wish to enjoy the music streaming in lossless quality.

Original (May 18th, 2021)

After recent whispers, Apple has officially announced lossless music and Spatial Audio support through Dolby Atmos for Apple Music users. These new features are aimed at allowing users to enjoy their favorite tracks and artists in the best possible quality. The best part of the announcement is that Apple will not be charging anything extra for the new high-quality audio.

It should be noted that you will need to be an Apple Music subscriber to be able to enjoy lossless audio. Apple will not be selling these tracks separately or upgrading your already owned tracks to lossless versions. The app will have about 20 million lossless tracks, to begin with, but the team is aiming to reach the 75 million mark by the end of the year. It is using Apple Lossless Audio Codec aka ALAC for encoding these superior quality tracks.

The Lossless tier starts at 16-bit at 44.1kHz i.e. CD quality but goes up to 24-bit at 48 kHz. There is also support for 24-bit at 192 kHz which Apple is referring to as Hi-Resolution Lossless. Once lossless audio becomes available, users will be able to choose their preferred sound quality by visiting Settings -> Music -> Audio Quality. One thing to keep in mind is that the Hi-Res tier can only be enjoyed using external equipment like a DAC. All other options can be played on Apple devices natively.

As for Spatial Audio with Dolby Atmos, Apple is hoping to deliver an immersive sound experience to the masses. It will work with all AirPods and Beats headphones that have an H1 or W1 chipset. It will also be compatible with "the latest versions of iPhone, iPad, and Mac".The format will work automatically when music is played through an Apple device's in-built speakers but if you wish to enjoy it through headphones, you will need to enable the functionality by visiting settings.

Apple says supported tracks will have labels next to them so that users can see if a particular song qualifies for the immersive experience or not. It will even create special playlists featuring Dolby Atmos songs so that users can find them quickly. Both these new audio formats will become available for all Apple Music users with iOS 14.6 and macOS 11.4 starting next month.