Apple routinely "stops signing" older operating systems to ensure users remain on the most secure and up-to-date versions.
is currently impossible through official Apple channels. Apple stopped signing iOS 13.7 on , shortly after the release of iOS 14. Download iOS 13.7 for iPhone SE
Because Apple no longer authenticates this software, you cannot install it even if you have the original firmware file. Why You Can't Download iOS 13.7 Apple routinely "stops signing" older operating systems to