To add a new page with the path domain.com/page in Next.js with the src directory, you do as follows:
In the src/app directory, create a new folder. If you want the page name to be domain.com/about, the folder name must be about. Inside the main directory of the about page, you need to name it page.js, page.tsx, page.ts depending on the language you are using: TypeScript, JavaScript. The page.tsx file is designated as the index page, so you must name it page.
Now, access the about page with the path domain.com/about or localhost:3000/about.