Look for a window and maximize it when found

maximize.rb

# `gem install win32-window` first
require 'win32/window'

puts "Searching for Notepad window..."

window = nil

loop do
  window = Window.find(title: /Notepad/)
  break unless window.empty?
end

window = window.first

puts "Found Notepad window with hwnd #{window.handle}. Maximizing..."

window.maximize

puts "Done!"