Hi! that is a beautiful pup there. Interesting color pattern.
I'm no expert, but I did get my own first GSD almost a year ago now. I have an older dog that we've had for years and years. We trained her ourselves and she turned out great.
But our GSD boy, he started out great, picking up the basics very quickly, walked well on leash etc. Then he got about 6/7 months old. He started pulling on leash when excited. He started coming only if he felt like it. Still would sit, down, kind of stay. Would bowl me over when opening door and started jumping on me and anyone else who showed him an interest. At this point he was nearly 70lbs. (he's huge)
I took him to vet for weighing and flea meds, when nurse walked down the hall to show us to the room, he ran after her, nearly pulled my shoulder out of socket and I almost fell down. There was no way I was able to stop him, he was too big, too strong. I realized my easy laid back manner of training (how I did it with my first dog) wasn't working and I needed help. Fast.
We put him in a 4 week boarded 'boot camp'. Yes it was hard. Yes it was spendy. Yes they trained us too.
Best money I've ever spent. He is now 1 yr old, still a work in progress. He heals beautifully. Sit, down, stay is great. Recall (come) is still a bit iffy if he is having fun. And he only jumps on those who let him. He seems to know who those folks are...
Personally I recommend finding a solid reputable training who has experience with GSD's and research/read about these great dogs.