Hi there hurley3p,
Thanks for connecting with us in Apple Support Communities! We understand the Files app is crashing on your iPad when you try to access PDF files with multiple pages. We're glad you're here, and we'd like to learn more to see how we can help.
To begin, is your iPad connected to a reliable Wi-Fi network when attempting to access these PDFs in Files? Are you accessing these PDFs from third-party apps within the Files app or are they saved to iCloud Drive? Have a look at this link to learn more:
Use the Files app on your iPhone, iPad, or iPod touch
Next, if you save one of these PDFs with the Books app, and access it in Books instead of Files, does that seem to make a difference in the behavior you're seeing when trying to access the PDFs? This support article provides step-by-step instructions for saving and importing PDFs with Books:
Save and mark up PDFs on your iPhone, iPad, or iPod touch with the Books app
Send over these details, and we'll take a closer look from there.
Cheers.