This greatly depends on language design and implementation.

For example, Clojure has all of these and much more, and it’s still much simpler and hassle free than rust. The functions are just functions, but the forms and lists that are very powerful.

functions are just

(defn foo [a b] (print "do thing"))

(foo 1 2)

With the power of destructuring that maps provide us, we can have named arguments:

(defn foo [a & {:keys [b c]}] (print a b c))

(foo 1 {:b 2, :c 3})

and for multi-arity functions, there’s no special syntax. It’s still just plain functions and forms

(def foo
  ([a] (print "I only have one" a)
  ([a b] (print "I have two" a b)))

It also has more advanced ways of polymorphysm with methods and protocols.

It depends on the design of the language.