Delayed environment variable expansion is NOT enabled by default. You can enable or disable delayed environment variable ...

Delayed environment variable expansion is NOT enabled by default.  You
can enable or disable delayed environment variable expansion for a
particular invocation of CMD.EXE with the /V:ON or /V:OFF switch.  You
can enable or disable delayed expansion for all invocations of CMD.EXE on a
machine and/or user logon session by setting either or both of the
following REG_DWORD values in the registry using REGEDIT.EXE:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Command Processor\DelayedExpansion

        and/or

    HKEY_CURRENT_USER\Software\Microsoft\Command Processor\DelayedExpansion

to either 0x1 or 0x0.  The user specific setting takes precedence over
the machine setting.  The command line switches take precedence over the
registry settings.

In a batch file the SETLOCAL ENABLEDELAYEDEXPANSION or DISABLEDELAYEDEXPANSION
arguments takes precedence over the /V:ON or /V:OFF switch. See SETLOCAL /?
for details.

If delayed environment variable expansion is enabled, then the exclamation
character can be used to substitute the value of an environment variable
at execution time.