This is a core block and thus available by default in Gutenberg WordPress editor. No download required.
WordPress Code Block in Gutenberg Allows you to display formatted code on a page or post. This is a simple block to display codes to your readers.
Code Block Features
This is a really basic block with almost no options in the toolbar or sidebar settings panel. Simply copy-paste your code and it will get displayed on the page as it is.
This is how it prints or output the code on the frontend.
This is how it works in the editor, a simple text area is available to paste your code.
Code block does not have any options in the sidebar as of now.