Realtek, Intel, and Broadcom all provide these as downloadable .exe or .zip files, typically titled Install_Win7_7130_07252019.zip . You put it on a USB stick using another PC, then run it on the offline target machine.
The gold standard for a Windows 7 offline network driver is 3DP Net , often paired with Snappy Driver Installer for a complete setup. The Recommended "Story" (Strategy) network adapter driver windows 7 offline installer best
Intel® Network Adapter Driver for Windows 7* - Final Release Realtek, Intel, and Broadcom all provide these as
Microsoft ended support for Windows 7 in January 2020. Consequently, major hardware vendors (Intel 12th gen, Realtek 2.5Gbe newer revisions) have stopped producing Windows 7 drivers. It supports Windows 7 and older hardware that
DriverPack Offline Network : A dedicated offline version of DriverPack specifically for LAN and Wi-Fi hardware. It supports Windows 7 and older hardware that manufacturers may no longer support.
So a truly useful offline installer is actually a :
