You can extract sxs folder from a Windows ISO.
An offline installer bypasses the internet entirely. This guide covers how to get, create, and use a .NET Framework 3.5 offline installer on Windows 10 and Windows 11. Method 1: Using Windows Installation Media (Recommended) net 3.5 offline installer
Note the drive letter assigned to the Windows media (for example: D: or E: ). Step 2: Run the Deployment Image Command Open the Windows Start Menu. You can extract sxs folder from a Windows ISO