I have pekins as well. No, they aren't built for surviving in the wild. They've been bred to provide a lot of meat at a young age - that process has been ongoing not for years but rather centuries. Pekins were domesticated 500 or 600 years ago. Jump forward to today and the end result is a bird with relatively high nutritional needs compared to its wild (or more wild) cousins and very poor ability to escape predation.
7-9# at full growth a year in. Supposedly they can get over 12#, but that has not been my (admittedly limited) experience. {Mine are from Hoover Hatchery, a very popular source for ducks obtained thru TSC and similar locations. Hoover is not famed for mass producing exceptional birds}.
Agree with the others, he was almost certainly dumped by some possibly well meaning but ignorant person. Beak and leg color varies thru the year, and is more pronounced in females. Diet has some effect as well, but a female pekin's beak and legs will get quite orange as they prepare to lay, then slowly fade as they produce egg after egg until they pause (and maybe molt), then gradually darken back to a respectable orange before laying again. I've paid less attention to the process in my (too many) drakes, but mine partially free range, so seasonal diet has more than the usual effect. So much so that I get greenish egg yolks in late fall when they eat more acorns...