Hi Vivek,
To enter Kerala you need the following two things:
1) An E-Pass
https://covid19jagratha.kerala.nic.in/
2) An RTPCR report not older than 72hours from time of collection. If you don't want to do an RTPCR test you will need to quarantine in Kerala from 14days.
Hope this helps!
Happy traveling.
Regards,
Senneil