Hi Hannakim!
Can you explain more about what you need this for? Modifying a page would require either access to the code (on the server) or to the admin panel. This is for security reasons, as I'm sure you can understand. Perhaps you are needing a better way to preview the changes on the frontend before they are live? Or maybe the tools in the Admin Panel cannot do the type of changes you are wanting? Explain a bit more about the goal, and I'm happy to help!