ios 16 update not coming , i thinks reason is back up

Bearing in mind that it might depends on your SE model (generation), see this compatibility list:

That said, assuming your iPhone can support a more recent iOS version, assuming you're trying to update your device wirelessly, and bearing in mind that to perform such a procedure you need to connect your device to a reliable and fast Wifi Network with Internet access (no cellular data, unless you use a 5G network, no personal hotspot on your device, no VPN connections are admitted, no Low Power Mode enabled, and I suggest that you keep the device plugged into power during the whole update process), read this support article:--> If your iPhone, iPad or iPod touch won’t update

Also, make sure your device is NOT running a Beta operating system version. Should be this case, you need to remove it before installing any official iOS/iPadOS releases, as per these instructions:--> How to uninstall iOS or iPadOS beta software - Apple Support.

DO NOT forget to create a full backup of your device before updating its operating system, and keep in mind that, depending on the available storage on your device and/or on your wifi network speed, it might take 30-60 minutes to complete the entire update process.

If the issue persists or if the iOS version currently running on your device is very old (from your product list, it seems that the device is still running the prehistoric iOS 13), try to update it via computer (if you don't have a computer borrow one from your friends/neighbors, or ask for help at an Apple Store or Authorized Service Provider), then learn how to update your device manually if you're using a Mac with macOS Catalina or later, or if you're using a Mac with macOS Mojave or earlier or a Windows PC.

If you still get no help, contact Apple Support directly, using this link:--> Get Support

Regards

Giulio

15.7.1 is a beta iOS version.

As suggested in my previous reply, you need to uninstall that version, using the instructions provided in my reply:--> How to uninstall iOS or iPadOS beta software - Apple Support.

And please, update your product list.

Thanks and regards

Giulio

For an iPhone SE 1st generation, iOS 15.7 is the latest iOS version.

Only an iPhone SE 2nd generation or later can be upgraded further.