When I was still brooding in the house, I'd handle the chicks frequently, just so they'd know they 'wouldn't die' if I held them.
Had a couple of Lt Brahma that never acclimated, they would continue screaming no matter how long or frequently they were handled. Lo and Behold one of those birds, at about 3-4 months old, got close to me in the coop by jumping on the nest perch. I reached out to touch her and she stood there, I touched her all over and she never budged, I picked her up and she was chill, she didn't wag her tail or purr, but she clearly enjoyed the 'cuddle'. I put her down and she walked away calmly. I was a bit gobsmacked. She continued to come up to me and stand there until I picked her up for a cuddle. This went on for a few months, I can't remember the exact timing, then she stopped. She was still pretty chill, as was her sister who did the same but less so. As much as I loved the look and demeanor of those birds, they were gluttons and lousy layers, and didn't fit the program here, so they had to go. Luckily they got to go to a pet home with little kids.