Enable Guest User in 10.14.x Via the Command Line (without a MDM)?
The first time the Guest user is enabled, a new user is created with a process similar to that of any user creation.

The macOS procedure has been distilled into a script, essentially running dscl . -create /Users/Guest and other dscl configuration commands on the user.

The script is available at


https://github.com/sheagcraig/guestAccount/blob/master/guest_account


and see the readme too for notes on Keychain. This has been tested to work in 10.14.2. Note that you will have to change or remove the OS version check if using on any OS above 10.8.