PDF Expert for iOS has a range of sorting options, such as name, date and size. What is even more exciting, you can actually sort the files not only in the My Files section of the app, but also inside folders and subfolders as well, and even on your cloud storage accounts added to the app.
In PDF Expert, you can sort your folders and files by one of the three criteria, either ascending or descending:
- Name
- Date
- Size
To change the sorting order, go to My Files 
section or any folder you created, tap ... at the top right, then select the preferred sorting order.
Note: Folders are always pinned to the top of the My Files 
section, subfolders are always pinned to the top of their parent folders.