Having a large breed is a big responsibility.
Please train your dog, it is not an option.
You should at least train your dog so he/she can walk on leash calmly when passing another dog, human, bicycle, skateboard...etc.
If you cannot control your dogs on leash you should not let them off leash, it is very simple.
A large powerful breed can cause serious damage when he/she is out of control.
Many such breeds are not for beginners with zero training experience.
These dogs are certainly not for someone who just wants to have a furbaby to spoil.
If you cannot control your dog, get some professional help.
Just like taking your dog to the vet when he is sick--training your dog is not an option; it is your responsibility.