How to find your lost iPhone in seychelles?

Same way that you would look for a lost phone anywhere else in the world. Use the Find My option in iCloud......assuming that you did set up the Find My option on the phone.

Keep in mind that the phone will not appear on the map unless it is powered on and has a good Internet connection. In other words, if the battery has run down, you will not see the phone on the map.

iCloud - Find My - AppleApple › Only on Apple › iCloud

You can use find my on the web.