I have an 18k pond that I recently finished, currently stocked with a little under 50 goldfish, comets, orandas, ryukin, etc. most of which are less than 2" in size. There are two 6" shubunkin who are "in charge".
I have the opportunity to accept some rescue fish, there are three full-size fancy goldfish, a ryukin, a black more, and an orange telescope eye. The bodies might be as large as lawn bowls, with huge flowing fins. If put on a scale, maybe they weight 30x the average size of the other fishes in the pond.
I'd quarantine the new fish for a month at least, but other than that, is it safe to introduce these huge fish among the smaller fish?