This is a common point of confusion for people. Julia has a useful and expressive type system, so people just assume it must be static but it's not, julia is dynamically typed.

It's intermediate representation is statically typed, but the language itself has dynamic semantics.

That said, we have almost every trick and tool up our sleeves that static languages have (in various stages of development). Check out https://github.com/aviatesk/JET.jl if you want static typechecking of julia code.