How to generate logstash-forwarder key and crt with TSL version 1.2

Currently our Logstash server and client are getting communicated with version TSL version 1.
We need to generate new cert and key files using TSL version 1.2 using openssl.

Can some one suggest me how to pass TSL version 1.2 while generating cert and key files using openssl on RHEL vm?