How do I make it so once i beat a level, i unlock another level but it's only shown in the menu?

So, i'm making a plane game, and i wondered how i can make the it so once i beat the easy difficulty, i unlock the next difficulty, but once i beat a level, it doesn't immediately bring me to the menu, but instead showed a felicitation screen that you can exit, i wonder how i can make it show the 2nd difficulty when i press on the difficulty levels instead of the moment i beat the game

This sounds easy to do but I guess no one responded because the phrasing is confusing, too many questions and it's not totally clear what you want.