Train him to heel in a fenced area. If he pulls, stop and make him come back to your side. Reward good behavior

That’s a good looking strong dog!

Counterintuitive, but a longer leash. My last dog would always pull on a 6ft leash but at 15ft of lead he rarely pulled.

“Become a tree.” Start walking, and whenever the leash becomes tight, you simply stop, plant yourself like a tree, and don't say a word. Took a while but it worked for my pup years ago.