Download iOS 14.2.1 (18B121) for iPhone 12 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 iPhone13,4
iOS Version 14.2.1
Release Date 2020-11-19
Update Date 2020-11-17
Sha1sum
23de8dbffa0b0ce3caad60e6732bbf11f85ea482
Sha256sum
8cee4ef1fcbeb56de8f748a007ca0d420a9a27ebbdc67e5be2a2d11b099d434b
md5sum
83e1d67d46a27642cdd71558832bf5e1
Size 5.13 GB
FileName
iPhone13,4_14.2.1_18B121_Restore.ipsw
Status

Download IPSW (5.13GB) Check device info
Release Notes

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

iOS 14.2.1 addresses the following issues for your iPhone:

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

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