When do boys stand up to pee

My son is almost 6 and still sits when he pees. That’s just how we taught him, I wonder when boys start to stand up but I think that’s a learned thing right?

They should start that from the beginning?

How is he going to change the sitting down habit now after a few years of sitting?

I’m confused someone help lol. I’m feeling bad I taught him to sit but I didn’t think anything about it at the time.