iOS 16 will bring a new feature related to eSIM cards which has not yet been publicly announced.
Currently, switching iPhones means you need to request a new eSIM from your carrier and register it. However, the iOS 16 developer beta suggests This one users will be able to transfer their eSIM settings via Bluetooth.
iOS 16 would give users the option to transfer eSIM settings to the new iPhone when setting up the new device.
Now, for this feature to work, users will have to wait for the network operators to support this feature. As iOS 16 is still in beta for developers, it is unclear what stage support from telecom network operators is at.