Nystul’s Magic Aura can make it so that magic and spells treat a creature as though it were another creature type. However the extent of this effect is ambiguous.
At first, it says the following, which specifically mentions spells which “detect creature types”. One could argue that this means it only affects information gathering spells.
You change the way the target appears to spells and magical effects that detect creature types, such as a paladin’s Divine Sense or the trigger of a symbol spell.
Then it goes on to give a far more general rule:
You choose a creature type and other spells and magical effects treat the target as if it were a creature of that type or of that alignment.
One could use this to change one’s effective creature type to something like Dragon or Celestial. This would seem to make you immune to spells that require a humanoid target, such as Dominate Person, as well as magical monster abilities which require a humanoid target, such as the Vampire’s Charm ability.
One could argue that Nystul’s Magic Aura is intended to only fool spells which gather information, but one could also argue that any spell which only works on a specific creature type is one which gathers information, even if that is not its primary purpose.
Which is right? Would Nystul’s Magic Aura make you immune to Dominate Person?