Elixir compiles to bytecode for the Erlang VM (BEAM). I would put it in the same relationship category as Clojure and Java or Kotlin and Java. Different language but there's a lot of synergy in the libraries/ecosystem/etc. If something goes wrong in your Elixir application it would be a really good idea to understand Erlang and BEAM.
I can't speak to Kotlin, but Clojure : Java :: Elixir : Erlang doesn't seem like a great analogy. Clojure and Java have very different philosophies, while Elixir has virtually identical semantics to Erlang.
Yeah, I learned LFE a few years back after years of (sadly only) hobby Erlang programming. I don't think anything in it surprised me. It felt very much like: What if Erlang's syntax were replaced with sexprs and we used Lisp-y style macros? Clojure's relationship to Java is nowhere near the same.
Knowing Erlang + Scheme and CL, LFE like exactly what I expected, with a strong Erlang vibe. Knowing Java + Scheme and CL, Clojure felt nothing like Java except that it could access Java classes and objects.
At its core, Elixir is effectively a wrapper of Erlang but with small tweaks/wrappers of the core library, Ruby-ish syntax, piping with `|>`, Mix project management, Hex package management, ExUnit for testing, and several other quality of life improvements. Elixir can easily call Erlang code, which is not easy the other way around. The biggest difference is that Elixir has a vibrant community, big projects like Phoenix, LiveView, and Livebook.