Need a help for jump down from platform in 2-5d sidescroller

Hi Again Fellows Devs!

I need a bit of help here, let explain a bit. I have this problem, I want to make the character the ability to jump down from a bridge to the lower floor. Can you help me with a clue or a tutorial?

azsdf2.jpg

Here in this draw you can see what I want to do. thanks a lot for your time!

In the platformer games of my childhood I was usually holding jump button and bottom arrow to tell the game I wanted to pass through such a platform. Instinctively I would say the platform has an overlapping collision. On begin overlap with the player, if he’s not holding the right inputs, turn the platform to real collision or do nothing.