How to create negative rounded edges

I’m sure this has been answered before but I don’t know what to search for.

Imagine a simple L shaped form with some thickness, a cube with two extruded sides making the L. I know how to bevel and round the outside of the L angle, if you see what I mean, but how do I make it round on the inside, a negative roundess (so it becomes a curved L)?

Im not sure what your describing.

They want a negative bevel like you can get in something like C4D or Modo. Not sure if it’s possible with Blender bevel at the moment…

This is what I get by just bevelling the inside edge in the usual way:


Can you be more precise about how what you want differs from this?

Best wishes,
Matthew