You can perform a defaults write on the macOS loginwindow preferences to set the Login Window text from the command line:

The screensaver engine on a Mac can be invoked from the command line. This can be useful for locking a Mac remotely if its security settings are configured to require a password after waking, but without needing to put the Mac fully to sleep:

The pmset utility can be used to sleep the display of a Mac from the command line. This can be useful for locking a Mac remotely if its security settings are configured to require a password after waking, but without needing to put the Mac fully to sleep:

The createinstallmedia utility can be used to create a bootable macOS installation disk, which is useful for installing macOS on multiple Macs without downloading the installer over the Internet each time:

The pmset utility can be used to schedule repeating reboots, replacing MTWRFSU 04:00:00 with your desired day(s) of the week and time of day:

The installer utility can be used to install .pkg software installation files from the command line:

The spctl utility can be used to manage the configuraton of macOS’ Gatekeeper security system.

The fdesetup utility can be used to manage which users are authorized to unlock FileVault encrypted boot volumes:

The fdesetup utility can be used to remotely restart a Mac without needing physical in-person keyboard access to unlock FileVault on the next boot only:

Apple Remote Desktop can be enabled and configured via the command line: