I remember a teacher telling me that Auburn has this special rule where if you get a certain test score on SAT/ACT, they will charge you instate tuition instead of out of state even though you are out of state
You can look around their website and see what they offer. My son started in 2013 and that was not an offering at that time. They do, however, participate in the Academic Common Market amongst a number of southeastern states - basically if there is not a school in your state that offers the degree you are seeking then if Auburn offers it and you fit within the stat paremeters you can attend for instate tuition for that degree only.
And of course their regular merit scholarships might get you there or close as well, but again, all that information is on their website.
I don’t think that it is quite the way you are stating it - not automatic based on scores. However, those scores qualify you for different levels of scholarships that bring the tuition down quite a bit - you still have to apply for the scholarships through AUSOM. Check out their webpage for merit scholarships for out of state students. For instance, I know a Presidential Scolarship is $18,000 a year with a 33-36 ACT/3.5 GPA, and there are others below that.