I bought a new Apple X and travelled outside my home country now I am not able to make or received any calls as it is not picking any local networks !!!

Hi there, Bahaah!
Thanks for reaching out to the Apple Support Communities! It sounds like you have an issue with connecting to local networks while traveling internationally and I am happy to help out! Based on what you are describing, it sounds like you are having issues while you are roaming. I suggest taking a look at this article About cellular data roaming options for your iPhone and iPad. Specifically:

Get help when you have roaming issues during international travel

1. Turn on Airplane Mode for about 30 seconds. Then turn it off again and let your iPhone automatically select the best network.
2. If you see No Service in the status bar of your iPhone, open Settings and tap Cellular, or Cellular Data, or Mobile Data. Tap Cellular Data Options and make sure that Data Roaming is on. Then, to check that international roaming is turned on for your account, contact your carrier.
3. If the date and time are wrong after you arrive, go to Settings > General > Date & Time. Make sure that Set Automatically is turned on.

Still need help? If so, here's what to do:

1. Go to Settings > Carrier and turn off Automatic. Wait until available networks appear, which might take two minutes.
2. Tap the carrier that you want.
3. Go back to the main Settings screen and wait for your iPhone or iPad to connect to the network.
4. If you still need help, try a different SIM card or contact your carrier for more information.