Sure! If you know the configuration language its easy to write a configuration file. Command line interfaces are often used to format your configuration file in a very specific manner, one can think of the CLI as an abstraction to create configurations. Another abstraction above the CLI would be for example using a GUI to click buttons that build a your config.
Each tools has their pros and cons, usually GUI tools is the last tool to be updated with new changes while the command line tool is usually the first. Building configurations manually can also be slow and error prone if you are not making sure to use the same release version as the operating system you are configuring for, manuals are often updated at the same time as commands but might lag behind.