How to get the name of the layer on a map composer with a single layer?

Question

I tried

layer_property( 'layer', 'title')

I would like to return the current layer from the map instead of 'layer'. (or list of the layers on the map?)

Doesn't seems to works with

 layer_id

or

@layer_name

It's for a model composer, that's why i want it dynamics.