Most GSDs, even as adults, can be very high energy. Not like
Border Collie high energy for most, but every dog is different. The best you can do is meet different potential GSDs and see which one fits the best into your lifestyle.
My last GSD wasn't much more then a pup when I had to rehome her, but she was pretty high energy. It helped her to give her little jobs, things for her to expect daily, like sitting before being fed, letting me go out the door first, (which are small things but make quite a difference) and of course regular tennis ball sessions. lol
I hope you find who you're looking for. GSD's are an amazing breed.