I have the EX model and I don't see it in my menu.There are door settings for locking,unlocking etc. but nothing for beep or honk.
I am in the United States, obviously some Seltos's are set to lock/hock on single press of lock button and some only work by press the lock button 2x.
I have the "S" Model and the 1st image below is the menu for the door, but you have to keep scrolling down to see the “Horn Feedback” option & check it. If that doesn’t work or exist, then send a picture of your Keyfob . I see people in India making it work by quickly programming with the Keyfob buttons. Also, just curious if your horn “honks” at all when you press it or ever made any kind of sound?
If you have the 4-button key fob, Press & Hold the Lock button & then also press the Unlock button (right after that) & hold them "both" buttons for about 10 seconds (until see the front headlights flash 4 times). This is how you activate/deactive the Horn Sound on Lock in some countries.
Hope this helps, just trying to help.
Blake