How to set another homepage for website build by React

I deployed one website on localhost , with npm build / react , and I would like to select another landing page .

However im a newbie working with React and I dont know where to find the routes for the pages . I have the following codes in the public/Index.html , public/manifest.json , and package.json from root folder.
I tried modifying the homepage in package.json to another folder/.ts/.tsx files but without any success..

Any idea in how to find the routes to other pages and how to set the landing page to them for localhost server ?