There are two types of stages, 

Project stages which applied to all created projects as you can see below:

Task Stages: when you create a new project, Odoo will ask you if you want to create a task stages for this created project.

So you can create a new task stages per project or use the already created once by adding your project to the task stages as below:

To be able to see the task stages, you need to enable the developer mode from settings -> Activate developer mode then you can access the task stages as below:

Updated:

As I mention above the project stages are defaulted for all projects but the task stages will be empty for new created project.

Project task stages differ from project to another so there is no default task stages will be applied to your new created project.

When you open your new project, you will get a blank screen so you need to add the task stages or you can click on "see example" and select one of the example and press "Use this for my project" and the stags will be created.

 If you want to use already created task stages you need to go to Task stages and open the ones you want to use in your project and add your project in Projects field.

Sorry Abdou,

Yes it is stages. Odoo 16 enterprise.

Thanks