If your file is on your PC, you will first need to get the file onto an app on your phone (such as your email or Files app), then follow the steps for "How do I convert a file from another app?" You can do this in multiple ways, such as:

• Email the file to yourself, then open the attachment to the email in the mail app on your device.
• If you are using a Mac, open Finder and drag the file into your "iCloud Drive", the find the file using your "Files" app on your phone.
• Use a service like Dropbox that allows you to sync files between your PC and mobile device
• If you have a Mac, right click on the file and select "Share -> Airdrop" and select your phone as the destination