Layouts are present in app/apps/themes/default_theme/views/layouts
I have a frontend controller that renders layouts of different themes based on params. For now , lets assume it renders default_theme. But how do you set a default theme?

module MyEngine
  class FrontendController < ApplicationController
    before_action :set_theme_view_path
    layout :determine_layout

    def index
    end

    private
    
    def set_theme_view_path
      theme =  'default_theme'
      # Add both the layouts and views paths for the theme
      theme_layout_path = MyEngine::Engine.root.join('app', 'apps', 'themes', theme, 'views', 'layouts')
      theme_view_path = MyEngine::Engine.root.join('app', 'apps', 'themes', theme, 'views')
      prepend_view_path(theme_layout_path)
      prepend_view_path(theme_view_path)
    end

    def determine_layout
      theme =  'default_theme'
      "layouts/application"
    end
  end
end

How do you dynamically render a layout at runtime? In my case , just a particular layout from another folder instead of conventional layouts inside views folder?