IOS 15.1 update not iPhone Se old ?

You realize that you are attempting to update a BETA version of iOS 15.2, right? This is not the right forum to discuss BETA software. You have a beta profile for developers installed on your iPhone. If you want iOS version 15.1, then you will have to remove the BETA profile and then reboot your iPhone. Once you complete the removal, then you can check for updates again and you should be able to see the official release of iOS version 15.1 for your iPhone.

One thing that you must also realize is that you do not have enough storage space to install iOS 15.1 or any versions of iOS 15. Create some free space on your iPhone (more than 6GB) and then try again.

Axel F.

This is not the right forum to discuss beta

When you experience an issue or something that does not work as expected in beta, send your feedback directly to Apple with Feedback Assistant.