Save the audio file you want to the phone, then open Settings, Sound and vibration (the name varies by brand), Phone ringtone, and look for Add or My sounds. Pick your file and it becomes the ringtone. Short clips work best, and MP3 is the safest format.
Android is the easy part; finding a sound that is really yours is the hard part. Ringoz writes an original ringtone from a name and a short line, sings it in one of twelve styles, and can set it on Android from inside the app, for the whole phone or for one contact.
Related questions
How can I make a ringtone with my name in it?
Record or generate audio that says your name, or use an app that sings it.
How do I make a ringtone from text?
Turn the words into audio (spoken or sung), keep it short, set it as a ringtone.
Can AI make a ringtone for me?
Yes. AI apps can now write and sing an original ringtone from a few words.