
There is no such breed as a toy Fox Terrier, suggest you have a look through
this list of KC recognised Terriers. There are also a number of smaller working breeds not recognised by the KC, but these have generally been bred for working & don't necessarily make ideal pets. Fox Terriers aren't particularly big dogs anyway, so I don't know why you think smaller might be better. I would say temperament rather than size is more important with Terrier breeds - depends what you are looking for in a dog & how much experience of dogs in general that you have.