The most important thing is to remember that the viewer needs to be sucked in and not distracted by sound. So, just fix that beginning so that the volume does not jump in one go. For the rest, make sure you have -2db headroom (via the ceiling on a limiter) (no need for true peak). Try also not to go over -8 lufs and get more than -11 lufs on the loudest part.
Phones tend to not do well with very hot songs (loud and no headroom). I am not sure if Instagram or Tik Tok etc does loudness normalisation.