You can find the song on YouTube, copy the link, and use an online converter (like y2mate, savefrom.net). Many of these sites have pop-up ads or risky downloads. Use an ad blocker and scan the file with antivirus before using.
Similar to Android, search for "Mai Chahta Hu Tujhko Dilo Jaan Ki Tarah Ringtone" on websites that offer iOS-compatible ringtones, like Zedge, iRingtone, or Mobile9. You can find the song on YouTube, copy
Once converted, import it into the section in iTunes and sync your iPhone. Tips for a Good Ringtone Experience copy the link