Unable to find or install amazon-linux-extras

I am trying to install nginx on AWS EC2 instance. As this is done using amazon-linux-extras as per AWS documentation, I tried that. But I am unable to find the package or install it using yum install(it says that the package is already available but I am unable to find it using ‘which’.

Below is the terminal output. Please help.

[arjun@ip-172-31-32-27 ~]$ which amazon-linux-extras

/usr/bin/which: no amazon-linux-extras in (/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/home/arjun/.local/bin:/home/arjun/bin)

[arjun@ip-172-31-32-27 ~]$ sudo yum -y install amazon-linux-extras

[sudo] password for arjun:

Loaded plugins: extras_suggestions, langpacks, priorities, update-motd
amzn2-core                                                                                                                                                               | 2.4 kB  00:00:00

Package amazon-linux-extras-1.6.9-1.amzn2.noarch already installed and latest version

Nothing to do