Download iOS 15.2.1 (19C63) for iPhone 6s

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

❌ This IPSW firmware is not being Signed by Apple

Firmware Identifier iPhone8,1
iOS Version 15.2.1
Release Date 2022-01-12
Update Date 2022-01-08
Sha1sum
af7d38b552dda764d35d6e92885de839ed7bf1fb
Sha256sum
89764e31ed76383ef189a09f7cb1e8c572bed931737b99372e1f2a756961cfb5
md5sum
a98b1b3eff1a455807a5331afea1a604
Size 5.07 GB
FileName
iPhone_4.7_15.2.1_19C63_Restore.ipsw
Status

Download IPSW (5.07GB) Check device info
Release Notes

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

iOS 15.2.1 contains bug fixes for your iPhone including:

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

https://support.apple.com/kb/HT201222