You’ll need to go to the Windows 11 Start menu, type Registry Editor, and then step through the folder file tree much like you’d do in the Windows 10 Settings menu. Here’s the directory you’re looking for: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced

Once you’ve entered the “Advanced” folder, right-click to create a “New” DWORD (32-bit) Value.

Name it Start_ShowClassicMode. Then right-click that value, select Modify, and set the “Value Data” to 1. You’ll then need to restart your computer.