Are Redist Install Packages from Steam offline installs?

The redistributables are quietly/silently installed using commandline switches/flags. This makes it slightly faster & less annoying as it doesn't have to show the installer window or wait for us to click through the installer.

With "SteamWorks Common Redistributables" (SCR) they are setup by devs, but the install scripts and redistributable installers themselves are managed by Valve. The devs can apparently still manage their own installscript.vdf to do this, but it'd be much easier to just opt-in to SCR.

The installers themselves seem to use whatever names they were given by Microsoft or whomever develops & licenses them to others, so if it's a web-based installer it should be obvious (if you can find it in the Steam folder). e.g. "dxwebsetup.exe" vs "directx_MonYear_redist.exe".

I can't check as my PC is dead, but there's no good reason for Valve to use web installers, and in my years of poking around I never saw a web installer for a redist in any of the few hundred games I installed.

That being said we do need to note that devs can include custom or uncommon redistributables that they will package with their game. So, yes it's still possible to have web-based installers from the devs, but very unlikely because of bandwidth costs.