How are actually the pictures behind NFT collections created? How do you create 10'000 pictures with different attributes? Can you program photoshop?

I never understood that part about creating a collection. The uncle of my girlfriend is creating amazing physical art that would fit well to the internet culture and he never got recognition for it. So I was tinking if we could create a collection out of one of his paintings (of course only if he is in). So is that all done with photoshop? Are there tutorials to do this? Will a normal graphic designer know how that works?

Thank you for any help