Any way of doing this through the command prompt without using any third party software or relying on powershell?
A simple command would be great like on Linux/Mac which I use
Use the Invoke-WebRequest module in powershell. For example:
Edit: I misread the question and thought you needed to use Powrshell.
There is no built in command in cmd.exe to return a public IP address. But you can use nslookup to resolve it, like so;
nslookup myip.opendns.com. resolver1.opendns.com
Another option for the OP:
telnet curlmyip.com 80
Type "GET" after you are connected.
Note: telnet is not installed/enabled by default on Windows.