See, eg, https://ask.usda.gov/s/article/Are-hormones-used-for-livesto...: “No steroid hormones are approved for use in poultry”
It’s certainly true that today’s meat birds are MUCH bigger than heritage breeds, but that’s a result of selective breeding, not hormones.
The size difference is stark, so I still wonder re: selective breeding.
“ Most broilers find walking painful, as indicated by studies using analgesic and anti-inflammatory drugs. In one experiment, healthy birds took 11 seconds to negotiate an obstacle course, whereas lame birds took 34 seconds. After the birds had been treated with carprofen, there was no effect on the speed of the healthy birds, however, the lame birds now took only 18 seconds to negotiate the course, indicating that the pain of lameness is relieved by the drug.”
Growth hormomes.
As an example, I've seen some US chickens as large as Canadian turkeys...
So free range, may not be getting growth hormones in the feed...