Add "Open with CMD" option to the Windows 10 context menu (both when right-clicking on a folder and in a folder).

cmd.reg

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Directory\Background\shell\OpenWithCMD]
@="Open with CMD"
"Icon"="C:\\WINDOWS\\system32\\cmd.exe"

[HKEY_CLASSES_ROOT\Directory\Background\shell\OpenWithCMD\command]
@="cmd.exe /k cd %V"

[HKEY_CLASSES_ROOT\Directory\shell\OpenWithCMD]
@="Open with CMD"
"Icon"="C:\\WINDOWS\\system32\\cmd.exe"

[HKEY_CLASSES_ROOT\Directory\shell\OpenWithCMD\Command]
@="cmd.exe /k cd %1"

For the "Icon" value I suggest you don't hard code the possibility variable path / drive like C:\ or D:\

%SystemRoot%\System32\cmd.exe is more flexible although even that is unnecessary. %ComSpec% alone is enough.

Also adding "open with cmd" to any file seems unreasonably dangerous... "open cmd here" feels more reasonable