In iphone 13 my Airtel network is not coming just in iphone 13 only if I use another iPhone means networks comes

Your phone appears to be locked to a different cellular provider.

Where was the phone purchased?

What is the model number at: Settings - General - About - Model = ??

What did your carrier say about this when you contacted them?

If you are having problems with your airtel network connection, you should contact them for help.

As I said, if you have an iPhone 13 that does not connect to the airtel network, then you need to take that phone to them to determine why it won’t connect to their network.