I did a quick Google search and this is what it said:

"AI Overview
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To extract and manipulate .pack files, you can use 7-Zip and its Grit7z plugin:
Use 7-Zip to open the archive
Use the Grit7z plugin to open, modify, or create the .pak archive
You can also create a .pak file by dragging a mod folder onto the UnrealPak-With-Compression.bat."