How to create menu of only submenu items -once selected

After I’ve created my main top level menu, instead of the submenu items showing as a drop down, I’d like them to show in a seperate menu after going to the top level menu item’s page.

Another way to explain this is if I click on a top level menu item and go to its page, then it will show the submenus for that particular menu item in a separate menu.

One way I can think to do this is to create seperate templates, but that doesn’t seem like a very good solution.

Or alternatively I have tried plugins eg advanced menu widget and flexi page widget, but they don’t do it exactly as I have descried.

I have also thought that it can be done by setting it up using a widget and assigning it using widget logic plugin or widget context plugin, to the different pages, but again, I think there might be a better solution to this.

Any thoughts on the best way to achieve this?

Thanks