Hi, do you mean in some form like csv or xml? There is no feature for that and you might need to develop your own addon for Foodlist (built-in hooks should be enough for that).
If you want to do this just once, you can change the templates and put shortcodes of the menus on the same page, and then manually copy and paste the output.
I just want to download PDF with all/selected menus together. Currently it is allowing me to download specific menu only.
Downloading as a PDF is definitely not a built-in feature of Foodlist. So, you should check with the plugin that provides you that.
If you can’t solve the problem yourself, I can offer you my services.