The express generator is a tool to generate your express js app. By default the express generator will use Pug, but it would be quite easy to change it to something like Ejs. And you can of course just remove the front end and do something yourself like express static or an framework like react or even directly returning something different based on the express endpoint. My point is that you can change your generated project like you could just manually create any express js project.
I personally prefer to just create the express project myself because I really dislike the format that express-generator uses for the creation of your project. It is a good template to work from when you are not experienced, but if you are experienced, my advice is not to use it.