This seems to be dependent on the Android version. My old Samsung phone has Android 10, the new one has Android 12.
Both have the same Samsung Music App V 16.2.27.5 installed.
Only on the Android 12 phone I could find
Samsung Music Settings 》Manage Playlists 》Export My Playlists
and
Samsung Music Settings 》Manage Playlists 》Import Playlists
Settings can be found in the three dots menu (...).
The playlists are stored in *.m3uformat in the internal memory, directory Music.