I will buy the mobile phone from your official website. Will it work on every network that follows it? It will work on the Egypt network

There are no international iPhones. Apple cannot guarantee the phone you buy will work on all networks, especially if by “networks,” you mean cellular plans. You can check which cellular networks are available in your country of choice. Are your planning to buy the iPhone from the Apple Store web site while in Egypt?

Find wireless carriers and worldwide service providers that offer eSIM service - Apple Support