Office 365 Offline Installer -

: If you are working with specific versions like Office 2021, see the Install or Reinstall Office 2021 Guide for compatible offline methods.

If you need to install Office on 10 computers in a lab or office, the offline installer saves bandwidth and time because you download once and copy to a USB drive. office 365 offline installer

The installer itself works offline, but (every 30 days or so for retail licenses). You cannot use it forever without internet. : If you are working with specific versions