Nginx reverse proxy with multiple outgoing ip


I’ve newly configurated Nginx reverse proxy.
My config file looks like this:

server {
    listen 80;
    location / {
        proxy_pass htpp://instagram.com ;
    }

server {
    listen 81;
    location / {
        proxy_pass htpp:/twitter.com ;
    }

server {
    listen 82;
    location / {
        proxy_pass htpp://youtube.com ;
    }

I would like to add multiple IP addresses to make a connection to Instagram Facebook or etc. address. I’m not familiar with Nginx or Squid proxy.
I want to be much more clear to explain it as much as I can.

I have several IP addresses are and I already added those interfaces to my server; also I would like to use different interfaces/IP addresses with each routing.

server {
    listen 82;
    location / {
        proxy_pass htpp://youtube.com ; # I would like to use uniqe addreses for each connection
    }

Long story short

Request reach to Nginx server
Nginx listens to port 82 and route with new interface/IP addresses

Request reach to Nginx server
Nginx listens to port 81 and route with new interface/IP addresses

I would like to apply this scenario but I’ve don’t have the know-how to do that.
I’m fully opened to any idea or advice.