How old is my phone
Selling my iPhone 11 how do I find out when I bought it.
iPhone 11, iOS 14
Question marked as
If it is less than 12 months old you can see when you activated it in Settings, General, About, Limited Warranty
In Settings Cellular/Mobile Data, right at the bottom you may have a last reset date which is your activation date if you never reset it manually
Or there's your receipt email from the retailer or Apple.com