Hi Krishna,
Welcome to Microsoft Q&A platform.
You can connect multiple Azure Virtual Machines with a single firewall IP by using Azure Load Balancer. Azure Load Balancer provides inbound NAT rules that allow you to map a public IP address and port to a private IP address and port on a virtual machine. This way, you can connect to multiple virtual machines using a single public IP address.
To assign each virtual machine's IP address to different users outside, you can create multiple inbound NAT rules for each virtual machine. Each inbound NAT rule maps a public IP address and port to a private IP address and port on a virtual machine.
Here is a tutorial on how to create a multiple virtual machines inbound NAT rule using Azure Load Balancer: https://learn.microsoft.com/en-us/azure/load-balancer/tutorial-nat-rule-multi-instance-portal
Hope this helps you.