Congrats on your new baby.
To rule out any disease/illness, I always recommend having a new bird thoroughly checked by an avian vet.
If you JUST brought her home, she may be a bit stressed and unsure of her new home/environment. Stressed birds do tend to ruffle up their feathers.
Good luck with her.
He could just be tired from the trip home/is adjusting to his new home (assuming you brought him home in the last 24 hours or so) OR he may be ill. You did not specify whether he is a baby or a older bird who is being rehomed, but it is not uncommon for rehomed birds to come home with some illness. The only way to know for sure is to take him to an avian vet. They can look him over and run any necessary tests/provide treatments. With birds, possible illness is nothing to just "wait and see" on. They can die within a day of a common cold. I would make an appointment with the vet ASAP just to be safe rather than sorry.
Our BFA (who was an older rehome bird) came home with a upper respiratory infection. He needed 2 courses of antibiotics to clear the infection. Had we NOT taken him to the vet as soon as we got him, he may have ended up needing more expensive treatment than just some antibiotics or even worse, not be with us anymore. He's been perfectly healthy since, but it is VERY important to take any new bird to a vet as soon as possible after getting them. Best to get started off on a healthy path then end up with serious issues down the line.