This is a really great book to use „in the real world“. It puts an emphasis on introducing clean code standards within a team and how to use different tools to ensure the standards are kept / will automatically be applied.
But if you are new to PHP and/or software development I‘d recommend reading „PHP 8 - Objects, Patterns and Practice“ by Matt Zandstra first, as „Clean Code in PHP“ does not have the space to explain especially patterns in detail.