How to open the default camera in perspective with another perspective three-dimensional window in MAYA, can you?

I don't quite understand what you mean, but I guess you want to have two windows, both of which are default cameras. Click the space in the perspective case, and four windows will appear. Hold down the space in any window, click the left mouse button at the MAYA logo in the middle to select the viewing mode, and the perspective mode is right above.

Or there is a panel in the window menu, and select the camera in the first menu.