Hello there Dinorah,
Thanks for posting here on the Apple Support Communities! This is a place where other Apple users can submit questions or respond to others to help lend a hand. Let's take a closer look as we do our best to provide some additional insight.
To get started, by menu bar, are you referring to the Dock at the bottom of the screen that holds apps? What exactly are you trying to do with it? The more detail you can provide, the better us and the rest of the community will be able to assist.
Otherwise, if you just want to change the size of icons on your Homescreen to include the Dock, go to Settings > Home Screen & Dock for more options.
We hope this helps get you pointed in the right direction.
Take care.