Hello whoisziggy,
I understand you're trying to download a file to your iPhone from Safari via the Files app. I'm happy to provide you with some steps to help you get that file on your iPhone successfully.
To answer your question, yes, files would be downloaded to the Files app where you could preview them there (depending on which type of file it is). Once you have a file in the Files app, you can save it locally to your iPhone using the steps in Use the Files app on your iPhone, iPad, or iPod touch, specifically this section:
You can find locally stored files in On My [device], under Locations. On your iPad, simply drag files into the On My iPad folder to store them directly on your device. If you want to save a file locally on your iPhone or iPod touch, follow these steps.
- Go to the file that you want to store on your device.
- Tap Select > the file name > Organize
. - Under On My [Device], choose a folder or tap New Folder
to create a new one. - Tap Copy.
You can also long press on a file, choose Move, and select which folder you want to copy it to.
On iOS 12 or earlier, tap the file and choose Move. Then, under On My [device], choose Numbers, Keynote, or Pages, and tap Copy."
You should be able to open the file as long as you have a compatible app on your iPhone it's able to open within. I recommend taking a look at the rest of the sections in the support article above as it has a lot of helpful information about using Files.
Thanks for using Apple Support Communities.
Take care!