How do I find my SIM card number on my iPhone?
[Re-Titled by Moderator]
Apple Vision Pro
Which number are you looking for exactly?
The phone number is provided by your carrier when you get service from them for your second sim.
If you have already acquired service and have inserted or activated the sim on your iPhone, then you should be able to see the associated phone number in Settings ➜ Cellular / Mobile Data.
If you are referring to the IMEI number for the secondary sim slot, then that can be found in Settings ➜ General ➜ About ➜ (Available SIM) IMEI2