Do you mean a decoder that will let a loco
run at crawl speed, such as real switchers do
in yards? If so, just about any decoder on the
market would do that. You would have to set
the appropriate CVs to get that right.
You can select the 'wire in' decoders from most makers
that will do that.
Google couldn't find any decoders with a
special 'switching' mode other than above. But that doesn't mean there isn't any.