Welcome to the forum. This would have been better posted in the IOS forum, but I'm sure a Mod will come along and move it.
There is no menu bar in Pages for iPad, as far as I know. However, on the keyboard are four buttons that open menus with the options that would be on a menu bar. One has the font currently being used, one has sizing for characters, one allows for justification options and one inserts breaks and footnotes. Also, at the top right you will see three dots that open to a menu of options for what to display on the screen.
What is it in the menu bar you want?