O16 said:
The tag that I think to be the closest to what you are looking for is "big_dom_small_sub"; I don't know any other tag which combines size difference, some type o sexual behave and specifies the role of each partner.

Yeah, it's the combining of big_dom and small_sub, but I don't think there is a specific way to find those in conjunction with a specific fetish; I've yet to find one.