There are certain cards which help you get free tickets(not entirely free though)
Most famous ones are Vistara cobranded cards.
Eg Sbi Vistara Prime Card
You get the card at annual fees of Rs3500
With this you get 1 Vistara Premium Economy Ticket which would easily cost 8-10K INR if you were to book by paying
Additionally you get more Premium Economy tickets each time you hit a spend milestone.
1.5lakh spends in a year - 1 more ticket
3lakh - another ticket
4.5 Lakh- another ticket
8 Lakh - another ticket
In addition you get 1 upgrade voucher using which you can upgrade your ticket from category X to category Y. This is via the Vistara Silver Tier Membership which is complimentary with the card. It also gives 5kg addition baggage allowance
There are more such cards in market like idfc vistara, axis vistara (business class variant as well)