For those who are wondering where is the option make sure you have right app installed. It's
Kotak 811 Mobile Banking with 811 logo.
Secure UPI Money Transfer, Scan QR, Check Account Balance & Transaction History
play.google.com
I was also searching in the old Kotak Mobile Banking app at night.
In the new app I can see option under
Account-> Savings -> Scroll down -> Get a free platinum debit card with 811 Super / Upgrade to 811 Super
Official Link for 811 Super (More details and FAQs)
Apply for Kotak 811 Super Savings Bank Account online & 7%* interest p.a. with ActivMoney. Get a platinum debit card, FLAT 5% cashback & more.
www.kotak811.com