How can I know the WiFi MAC address before the iphone is activated?

Steven_Apple wrote:

Just got a new iPhone. In order to activate it, I have to get it connected to the home WiFi network. However, my network is configured with enhanced security which only allows devices with MAC addresses in the white list to get connected.

That mean that you use private Wi-Fi addresses.

You can assign the iPhone a MAC & a private IP address.

Log in to the router, add your iPhone NAME + iPhone MAC  + private IP address.

Your iPhone MAC address is: go to Settings -> General -> About ->the Wi-Fi address (note this address).

Assign a private IP address to the iPhone, for example 192.168.x.xxx or 169.254.x.xxx. 

This depends on the router & other iDevices that have already been added.

What is important, check the list and the last xxx must be different from the iDevices that have already been added.

See the following Apple articles:

Use private Wi-Fi addresses on iPhone, iPad, iPod touch, and Apple Watch

https://support.apple.com/en-us/HT211227

Recommended settings for Wi-Fi routers and access points

https://support.apple.com/en-us/HT202068

You could have set up your device through a cellular network, or iTunes to activate and continue setting up your device. 

WiFi is not mandatory for setting up as a new device.

Once set up, Settings > General > About [There you have it]