How can I set a ringtone from iTunes?

Use tones and ringtones with your iPhone, iPad, or iPod touch

Customize your ringtone, text tone, new mail alert sound, and more.

There are multiple sounds available on your iPhone, iPad, or iPod touch, but you can also buy ringtones and other tones from the iTunes Store. To buy ringtones and other tones, open the iTunes Store app, tap  More, then tap Tones.

Store availability and features might vary by country or region. Learn what's available in your country or region.

Change your ringtone

1. On your iOS device, go to Settings > Sounds & Haptics.
2. In the Sounds And Vibrations Patterns section, tap the sound that you want to change. You can change your Ringtone, Text Tone, New Mail sound, Calendar Alerts, and more.
3. Tap on the name of a ringtone or alert tone to hear it play and set it as the new sound.

You can also set a Ringtone or Text Tone for a specific contact: In the Contacts app, find and tap the specific contact, then tap Edit in the upper-right corner. Tap Ringtone or Text Tone, then choose a new sound.

Redownload previously purchased tones

With iOS 11 or later, you can redownload purchased tones that you bought using your Apple ID.

Go to Settings > Sounds & Haptics, then tap on any sound. At the top of the page, tap Download All Purchased Tones to check for any previously purchased tones that are not currently downloaded to your device. You might not see this option if you've already downloaded your previously purchased tones or if you haven't purchased any tones.

You might not be able to redownload some previously purchased tones.

Move custom ringtones from iTunes to your iOS device

If you have a custom ringtone or tone in iTunes on your Mac or PC that you want to move to your iOS device, you can manually add it to your device using iTunes.

1. Connect your device to your computer.
2. Open iTunes. Make sure that you have the latest version.
3. On your computer, find the ringtone or tone that you want to add to your device. If the ringtone or tone previously appeared in your iTunes library, you can find it in the Tones or Ringtones folders of your iTunes media folder. If you created a ringtone in GarageBand on Mac and then shared it to iTunes, it might be in an Import folder. 
4. Select the tone that you want to add to your device and copy it. (You can use a keyboard shortcut.)
5. Return to iTunes and go to the Library tab of Music.
6. Click your device in the left sidebar, then click Tones.
7. Paste your tone. (You can use a keyboard shortcut.)
8. 

You can also drag and drop your tone file onto the name of your iOS device in the left sidebar of iTunes.

Use tones and ringtones with your iPhone, iPad, or iPod touch - Apple ...

https://support.apple.com/en-us/HT207955