How to thicken a mask in Unreal engine 5??

I have a post effect that gets a nice exterior cel shading that silhouettes the characters, but I would like to apply it only to a specific character. I have created a “Mask With the Custom Stencil Buffer” but as it masks everything that is not the character it does not respect the outer line that makes its silhouette (and yes, the mask works perfectly, I have already checked it). I have applied it in several places on the material, but it is impossible to apply it the way I want. Finally, I have come to the conclusion that applying it here (see attached image) is the correct solution, since it is applied before the celshading is created, but it doesn’t seem to have any effect:

Can anyone think of how to do this correctly?

I leave here the result and how it should be:

Best regards and thanks in advance.

Solved, follow this tutorial: