Open the Files app
Tap Browse
Tap On My iPhone
Tap Downloads
Open the file you want
If you downloaded a file in Safari
Open Safari
Tap the Downloads icon in the address bar
Tap the downloaded file
If you downloaded a photo or video
Open the Photos app
Check Recents or Albums
If you downloaded an attachment from Mail or Messages
Open the app where it was received
Tap the attachment to view or save it
If you cannot find a download
Use the Search bar in Files
Check iCloud Drive
Check the app that created the file