A family of Microsoft word processing software products for creating web, email, and print documents.
How do you mean that the File tab is the default? Since activating the File tab means to hide the document content, are you saying that you do not see the document itself? Go to File > Options > General and clear the check mark next to "Show the Start screen when Word starts." This will force Word to start with a new, blank document.
If you are saying that the ribbon is minimized or not visible at all, see https://support.microsoft.com/en-us/office/show-or-hide-the-ribbon-in-office-d946b26e-0c8c-402d-a0f7-c6efa296b527.