From what I understand Apple music streams in ALAC format up to 24/192 resolution.
From support.apple.com:
If you subscribe to Apple Music, you can play and download music encoded using the Apple Lossless Audio Codec (ALAC), which makes files smaller while preserving all of the original data in the file. In Apple Music, lossless music is available in two formats:
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Lossless: Up to 24-bit, 48 kHz
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Hi-Res Lossless: Up to 24-bit, 192 kHz
Albums and songs available in lossless have the Lossless button next to them.
Note: Apple Music and lossless aren’t available in all countries or regions. See the Apple Support article Availability of Apple Media Services.