Download iOS 13.1.3 (17A878) for iPhone 11 Pro

You will have to note that you can only restore signed IPSW firmware files using iTunes or 3utools.

Firmware Identifier	iPhone12,3
iOS Version	13.1.3
Release Date	2019-10-15
Update Date	2019-10-10
Sha1sum	b606f56ce6b71466ca82df2c98c64246ccb4a4fc
Sha256sum	fe1b4c45ae2b945fc0a49ee5d9af4fcd800882429269bf014cdff7edeca562aa
md5sum	1866f3fe4e2a3b1c4e12fc0c25afcf4a
Size	4.28 GB
FileName	iPhone12,3,iPhone12,5_13.1.3_17A878_Restore.ipsw
Status

It should be noted that these are the official release notes for the from Apple

iOS 13.1.3 includes bug fixes and improvements for your iPhone. This update:

Addresses an issue that could prevent a device from ringing or vibrating for an incoming call
Fixes an issue that may prevent opening a meeting invite in Mail
Resolves an issue where data in the Health app may not display correctly after daylight savings time adjusts
Fixes an issue where Voice Memos recordings may not download after restoring from iCloud Backup
Addresses an issue where apps might fail to download when restoring from iCloud Backup
Fixes an issue that can prevent Apple Watch from pairing successfully
Resolves an issue where notifications may not be received on Apple Watch
Fixes an issue where Bluetooth may disconnect on certain vehicles
Improves connection reliability of Bluetooth hearing aids and headsets
Addresses launch performance for apps that use Game Center

For information on the security content of Apple software updates, please visit this website: