If you have a .rar file (often containing comic "panels" or pages), you can import it using several methods supported by Panels App :
Ensure your RAR file contains standard image formats (like .jpg or .png ). Panels is designed to read these compressed archives (often renamed to .cbr for comics) and present them as a seamless book.
You can use the app's tools to organize content into collections or subfolders if you are putting together a large series.
Move your .rar file into the "Panels" folder within the native Files app. The app will automatically detect and list it in your library.
To put together a digital comic from a RAR file in the reader, you generally need to import the file into the app, which will then automatically "assemble" the pages for viewing. How to Import and View Your File