Scala, 26 bytes

Saved bytes thanks to the comment of @corvus_192

Golfed version (26 bytes). Try it online!

a=>a.min*a.sorted.apply(2) 

Alternative:

//scala 3 import scala.util.chaining._ def f(a:Int*):Int = a.sorted.pipe(a=>a(0)*a(2)) 

Scala, 25 bytes

Saved bytes thanks to the comments of @corvus_192 and @user

Golfed version (25 bytes). Try it online!

a=>a.min*a.sorted.tail(1) 

Alternative:

//scala 3 import scala.util.chaining._ def f(a:Int*):Int = a.sorted.pipe(a=>a(0)*a(2)) 

Scala, 37 bytes

Try it online!

def f(a:Int*)=a.min*a.sorted.apply(2) 

Scala, 26 bytes

Saved bytes thanks to the comment of @corvus_192

Golfed version (26 bytes). Try it online!

a=>a.min*a.sorted.apply(2) 

Alternative:

//scala 3 import scala.util.chaining._ def f(a:Int*):Int = a.sorted.pipe(a=>a(0)*a(2))