Okay, so you're asking about where to find the newest Michael Vey book. The series has been a bit quiet, honestly, and I think the last main entry was 'Michael Vey: The Final Spark' back in 2018. There hasn't been a new novel since the series was supposedly concluded with that seventh book.
If you're looking to buy or read that one online, your standard ebook retailers like Amazon Kindle, Apple Books, Google Play Books, and Kobo will have it. Sometimes libraries have it through OverDrive or Libby too.
I remember picking up the hardcover years ago and feeling like it wrapped things up, even if some threads felt rushed. I'd check Richard Paul Evans's official site or socials for any announcements, but I haven't seen anything about a truly new book for a while now.