Download iOS 15.2.1 (19C63) for iPhone 13 Pro Max

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 iPhone14,3
iOS Version 15.2.1
Release Date 2022-01-12
Update Date 2022-01-08
Sha1sum
1d8d298dcf5d2d625923d25e92073c5a7a605030
Sha256sum
ef7502ef06bfb55e04da6a3f5f41e75d15ebdf82575ef998df54790e8b548cc6
md5sum
7e9435a9df834f763a88235b9014eacf
Size 6.20 GB
FileName
iPhone14,3_15.2.1_19C63_Restore.ipsw
Status

Download IPSW (6.20GB) 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