Emoticons/emojis not being sent via SMS
Several steps to the solution


Recipients should have Android Kitkat or newer to view the emojis.
The fonts in used on your Lenovo K6 does not support the emojis.
The Android 7 provided for your K6 does not support emojis.


You can't do much for any of the above cases as they depend on someone other than you. Wait until their side is rectified or a workaround is provided.

Solution that you can do!

Install an Emoji Android keyboard. Search for it in the playstore.