Record a silent ringtone or find a free one. Make that your default ringtone. Then adjust the ringtone for that contact. Ideally, you would be able to set a ringtone per contact group like you can with Android and other phones but not with apple.
Here are steps to create your own ringtone ref
How to Convert a Voice Memo into Ringtone for iPhone
Before you go ahead with the procedure, you’ll need to download GarageBand from the App Store. In order to use this technique to convert your audio recording into a ringtone, your device needs to be running iOS 11 or later. You’ll also need to record audio first using the Voice Memos app. Once you’re done, simply follow the steps below for making a custom ringtone.
1. Open the “Voice Memos” app on your iPhone.
2. Your previous recordings will show up here. Tap on the recording that you want to set as your ringtone and press the “triple-dot” icon for more options.
3. This will open the iOS share sheet. Tap on “Save to Files” to save this recording within the Files app.
4. Choose a preferred directory to save the recording and tap on “Save”.
5. Next, Open the GarageBand app on your device.
6. Choose any instrument that’s available. It doesn’t matter which instrument you choose, as the procedure is going to remain the same. In this instance, we’re choosing Keyboard.
7. Once you’ve opened the instrument, tap on the “project” icon as shown in the screenshot below.
8. Here, tap on the “loop” icon located at the top-right corner in order to open your audio recording.
9. Make sure you’re under the “Files” section and then choose “Browse items from the Files app”.
10. This will open your Files directory within the GarageBand app. Find and tap on the audio recording you saved in Voice Memos.
11. In this step, long-press the file name in order to open it in the project menu within GarageBand.
12. Drop the file as the second track, because the first track by default is reserved for the instrument you chose.
13. Now, tap on this track and drag the ends to trim the audio recording according to your preferences. You can play it back using the “Play” icon located at the top, if necessary. However, you might want to disable the annoying metronome by pressing the icon located to the right of “record” icon.
14. Once you’re done adjusting your clip, make sure it’s under 40 seconds in length. Now, tap on the “downward arrow” icon at the top-left corner and select “My Songs”.
15. Your GarageBand project will show up under Recents as “My Song”. Long-press on it to access more options.
16. Now, tap on “Share” as shown below.
17. In this step, select “Ringtone” in order to export your project as a ringtone.
18. Now, you can give the ringtone a name of your choice. Once you’re done, tap “Export” located at the top-right corner of the screen.
19. Once the export is successful, tap on “Use sound as…” in order to set it as your default ringtone right within GarageBand.
20. Here, you can choose to set it as your default ringtone or a text tone. Additionally, you also have the option to assign the sound to a specific contact. However, if you just want to add it to the list of existing ringtones, tap on “Done” instead.
Now you’ve learned how to set your voice recordings as a custom ringtone by using GarageBand on your iPhone.