Carrier
Where can I find the carrier to my iPhone, I go into settings but all it says is sim locked.
iPhone XR, iOS 15
See this Apple articles below:
How to unlock your iPhone for use with a different carrier
https://support.apple.com/en-us/HT201328
If you can't activate your iPhone
https://support.apple.com/en-us/HT201407
Where can I find the carrier to my iPhone
Go to -> Settings -> Mobile network -> scroll to Network selection you can see who your carrier is.