My understanding it is up to each conference.
Last year there was a three way tie in Union County for fourth place. Catholic, Weddington, and and Sun Valley were the top three teams. Max Preps adjusted rankings were not used! The conference had opted to draw straws to break ties.
It was pretty evident that Monroe and Marvin Ridge were the two best teams but Monroe had lost by one to Cuthbertson. Cuthbertson was way lower ranked than the other two. Fortunately, Cutherbertson, with a 3-8 record, lost out on the draw.
Here is the crazy thing. If Cuthbertson was one of the two schools to make it in they would not have been able to go to the playoffs while the other two schools, if selected in the draw, qualified. Cuthbertson winning one of the two draw slots would have knocked two teams out of the playoffs from the Southern Carolina Conference.
Cannot remember the exact reason but it was either (1) they could not go to the playoffs as a wild card over a school in their conference ranked higher than them that did not make the playoffs or (2) they were not a top 64 team (3) or a combination of those two items.
Go ahead and blame it on the NCHSAA and the system but any conference that is relying on drawing straws should look at that scenario.