#[Japt](https://github.com/ETHproductions/japt), 8 bytes

 á2 ËrbÃe

[Try it](https://petershaggynoble.github.io/Japt-Interpreter/?v=2.0a0&code=4TIgy3Jiw2U&input=WyJDb2RlIiwiR29sZiIsIklzIiwiQ29vbCJd)

 á2 ËrbÃe :Implicit input of array
 á2 :Permutations of length 2
 Ë :Map each pair
 r : Reduce by
 b : Get the index of the second in the first - 0 (falsey) if it's a prefix
 Ã :End map
 e :All truthy (-1 or >0)