German Shepard Puppy Training tricks
I would generally recommend leashing a puppy outside until their leash manners and recall are excellent and then only working off leash in securely confined areas. You can do some come when called work either indoors or in a small and securely confined outdoor space, that should transfer over to trips outside. You can also do some hand targeting work that could be a really fun game to get your pup interested in coming right to you. Effectively the idea with this is to teach your pup that being around you and coming when called is the greatest thing they could do. You have offer a more rewarding experience than what ever he is interested in outside. Whether that is achieved with treats or toys or getting to go for long walks, your puppy should feel that they are safest and know that the funnest things happen when they are spending time and focused on you. With a German Shepherd this should be pretty easy as they typically want to be very involved with their people. Some more details about the scenario in which he runs from you would help to see what more specifically you should work on and how. Like if he's running because he feels insecure about you grabbing at him. Or if he's being playful and trying to play tag with you.
Always keep on leash, especially if puppy! Even if he has good recall (which he doesn't) there may be something that startles him like a truck honking or dog running up that would require you to immediately have control over him. I don't recommend allowing him off leash until he knows and understands that when you say "follow" or "come" to do it immediately. That instant response isn't automatic, it has to taught and learned. You practice it until you know he will come 90% of time, *then you can start going off leash.
I also say leash him! Being off leash is an earned privilege that can be earned when your puppy has been taught a reliable recall. Start proofing a new recall word or sound (I use back), in the house with low distractions. Say the word in an excited, happy manner and treat heavily for coming. The first few times, make sure puppy is already looking at you. Recall training is all about setting him up for success, not testing how well he will listen. When he comes, lots of praise and yummy treats. It's a party! As he becomes reliable in the house, take the behavior outside on a regualar leash and then to a long line.It is always exciting when puppy returns to you. Then, you can try it in an open field with no distractions and finally move up to a high distraction setting. Also, when your dog gets a reliable recall and you, for example, take him hiking or to the dog park off leash, call him to you several times, treat and release him to go play again. Otherwise, dogs learn pretty quickly that when you call them, it means the fun is over and he may feel punished. Hope this helps.