Top x switch x bottom

In need of recommendations for the above trope. I have read this trope as side story and became more interested in this trope.

!The story goes like, At first, two alphas and one omega but 1 alpha goes under second differentiation and turned out to be enigma and that's how it became top x switch x bottom.!<

I thought, I could easily find stories based on this trope but I couldn't find a proper one yet.

So, looking for a story that features top x switch x bottom. If anyone has read please do share the name.