If you don’t want to download anything, you can use this free online web service Install On Air. This is often used when you want to share your beta apps with others for testing.
You just need to upload your IPA file to the Installonair website and generate a sharable link or QR code. Anyone can click the link or scan the QR code to install the IPA on his or her iOS device.
Since it is an online service, you can use this iOS IPA installer without a PC. You need to download the IPA file onto your iPhone and then save it to the Files app. Then you can upload it to Installonair from the Files app.
Install IPA Now at https://www.installonair.com/