greet.turbo_stream.erb

<%= turbo_stream.update "panel" do %>
  <% if params[:position].to_i <= 5 %>
    <p>Less or equal to 5</p>
  <% else %>
    <p>more than 5</p>
  <% end %>
<% end %>

hello_controller.js

import { Controller } from "@hotwired/stimulus"
import { get } from "@rails/request.js"

export default class extends Controller {
  greet(event) {
    let value = event.currentTarget.value
    get(`/home/greet?position=${value}`, {
      responseKind: "turbo-stream"
    })
  }
}

home_controller.rb

class HomeController < ApplicationController
  def index
  end
  
  def greet
    respond_to do |format|
      format.turbo_stream
    end
  end
end

index.html.erb

<div data-controller="hello">
  <input type="range"
    name="custom_range"
    id="custom_range"
    value="6"
    min="0"
    max="10"
    step="0.5" data-action="change->hello#greet">

  <div id="panel"></div>
</div>

routes.rb

Rails.application.routes.draw do
  get 'home/index'
  get 'home/greet'

  root "home#index"
end