Drupal 9

The advantage to installing Drupal using composer is that you can easily install other components, libraries, and themes which are designed to be installed using composer.

Installation Instructions:
Using your terminal, navigate to the directory that you are using to store your Drupal projects, and then run the following command:

For Drupal 9
composer create-project drupal/recommended-project:9.5.0 project_name

For Drupal 10
composer create-project drupal/recommended-project project_name

To create your first Drupal 9 theme, I recommend using the 9-step guide laid out by specbee, with a single edit to make the project work properly. On step 7, we are told to create templates/system directories, and create a page.html.twig file within the system subdirectory. This will lead to an error without feedback from the program, and your theme will not display properly.