No, it is not. DOCX is a more advanced and reliable format featuring improved data protection algorithms.
You can definitely decrypt an encrypted DOC file without finding the original password (for example, at AccessBack.com) by merely finding the proper encryption key.
But when it comes to DOCX it will simply not work. The only option is to methodically try possible passwords, one by one. And each new release of Microsoft Office file
format slows down the speed of brute-force attack.
The good news is that when searching passwords of DOCX files you can use AMD and NVIDIA graphics cards. It turns out much faster this way.