So yours is a "Chinese" silkie because its medium size and white?
I believe every chicken has had another breed in their background some time or another. Even the white silkies.
Every breed came from the jungle fowl so not sure the point there.
In other countries there are LF and bantam silkies. Here in the states our silkies are considered bantams but they're in between the sizes of the other countries.
If I wanted to make some big ones I think I'd cross silkie with large show type cochins.