This method is an old internet trick that works specifically on older RAR formats or simple numeric passwords. It involves converting the RAR file into a batch file to automate password guessing.

There is no universal "master password" built into WinRAR.

WinRAR allows users to encrypt file names. If this option was selected during archiving, you will not even be able to see what is inside the archive without the password.

WinRAR Password Unlock: Proven Methods to Recover Forgotten RAR Passwords