How to Overcome a Dog's Fear of Approaching People

With the gate he seems to like get mad if people approach him when he's behind the gate. He'll sniff and then he'll jump back and start barking. Backing up and barking is fear. It's him being afraid. So that's him barking at the UPS guy. Um where somebody does come in If the muzzle's on him then you can have him approach. But it's hard to tell people like hey um My 160 pound dog is gonna come up at you and bark at you with a muzzle on so just be chill. I think that's like the biggest hump. I have to overcome is making like I hate making people feel uncomfortable but yeah, well, I also know