How do I open Files in iOS 26 with Preview app?

Found a solution for this!

How to view PDFs and images in the Apple Files app by default (for iOS 26):

1. Open the Files app. Find a PDF file and touch & hold (long press) on the PDF file. From the pop-up menu, select “Open With” and choose “Preview with Quick Look.” Now, all PDFs by default will open in the Files app using Quick Look instead of opening separately in the Preview app.
2. Repeat the above step for images as well. You’ll need to complete this process separately for each image file type (JPG, JPEG, PNG, HEIC, etc.) as the new setting only applies to the specific file type that you clicked on.

Simply long press on the file in the Files app and select Quick Look.

It is really inconvenient. I wish I could erase that app PREVIEW from my phone, and I tried, and it was unbelievable the result, it started doing something weird while trying to open/view any image, each file —a pdf or image — it would launch a movie app. So I downloaded from app store the preview app, the magnifier icon now, and just hope they elminiate this thing. Thanks

It is really inconvenient. It pops up GIGANTIC. I wish I could erase this app PREVIEW from my phone, and I tried, and the result was unbelievable: it started doing something weird while trying to open/view any image. Each file—a PDF or image—it would launch a sort of movie, like adding movement. So I downloaded from the App Store the preview app to have it again (the magnifier icon now), and I just hope they eliminate this thing. Thanks

Why did Apple think opening an actual app to view a file in Files wasa good idea. I'm trying to find something fast. Ifi wanted to use Chunky or Procreate or VLC, i would have imported the file in the first place. I explicitly DON'T want to do that. Scraping hundreds of files that way is too bloody slow.

The new Preview app is absolutely TERRIBLE! Who designed this?! It makes no sense. How do you close a document you are viewing?

It doesn’t make any sense how they have separated it into an app that can’t be closed, among other issues.

Thank you !! Had the same question, thanks for the solution!