Oh i am sorry! I assumed that you were running the Apache server. WHM stands for 'WebHost Manager' and it allows administrative access to the back end of cPanel. WHM makes the server administration more comfortable.

For AWS (EC2 instance), you may need to manually install or upgrade your PHP version using command lines as already mentioned above by @RJ Arsenault

I don't know how you set your server but you can also have Linux or Ubuntu virtual server on AWS, and therefore, install cPanel & WHM AMI (Subscribe to it) in the AWS Marketplace (It should come with EasyApache 4). That will make the PHP installation easier.

Here are some good tutorials:

Building cPanel Web Hosting on Amazon AWS:

https://blog.cpanel.com/how-to-build-a-cpanel-hosting-environment-on-amazon-aws

cPanel on AWS MarketPlace:

https://aws.amazon.com/marketplace/seller-profile?id=0cd0aa0a-daa0-4b57-9bc5-dfffec41e1da

Launch an AWS™ AMI™ Instance - Amazon Web Services™ (AWS) cloud service and the cPanel & WHM Amazon Machine Image™ (AMI):

https://docs.cpanel.net/knowledge-base/web-services/launch-an-aws-ami-instance/

How to Install PHP 8 on AWS EC2 instance? ((There is a helpful video at the bottom of this article):

https://awswithatiq.com/how-to-install-php-8-on-aws-ec2-instance/

You can also google about the subject. You will find some good tutorials on both Google and YouTube.

Hope this helps!