Hello Rayan
Alias IPs are useful to containerized deployments in GCP[1][2]. It allows you to choose a range of private IP address(es) when you want a VM to host multiple containers that require routable IP addresses.
As I am not clear of your use case of your applications, if it is your webserver, at once Alias IP range is added, you should specify the IP or domain within the host configuration of your webserver. So when you request the internal IP you will be redirected to the "VirtualHost" pointed to the IP. You can follow this guide [3] for examples.
In case you have particular questions on Kubernetes applications, you can always refer to the appropriate discussion forum [4]
[1] https://cloud.google.com/container-engine/docs/ip-aliases
[2] https://cloud.google.com/compute/docs/alias-ip/
[3] https://httpd.apache.org/docs/2.4/vhosts/examples.html