the general rule of thumb is to get your master to -14 LUFS, but everyone i work with goes louder (me too), so -11 LUFS to -7 or -8 LUFS. personally am not really interested in dolby atmos until it (or something else) becomes a standard for all streamers.
so i do my masters as 44/24 stereo wav files. my experience is, everything works out fine (i've heard my work on spotify, tidal, applemusic, amazon, youtube).
mostly, trust your ears (and meters), and streaming services will adapt your mix to their requirements.